@Loopysue - It's a good video for maps where you have one or more scaled items in the part of the image you intend to use.

If there isn't something like that in the piece of map you want to copy, it's worth taking some extra time to construct an image that does have the correct scale in it - which will likely mean extracting and adding the scale into the map image in image processing software before importing it into CC3+. Key element is to ensure the two bits of the image don't get accidentally rescaled compared to one another before making the final PNG or JPG...

And also not to mistakenly cover some essential bit of the map with the scale...

DD3 has four different bitmap fill lava textures, Stone Lava Cooled, Stone Lava Flaming, Stone Lava Molten, and Lava. The Jon Roberts Annual Dungeon style has three, Lava, Lava Hot and Lava Cool. The Munson's Mines Annual Dungeon style has three different reddish lava bitmap fills. The Vandel Dwarves Annual Dungeon style has two reddish lava texture fills similarly. The Mike Schley Annual Dungeon style has a single lava bitmap fill. The Naomi VanDoren Annual Dungeon style has three, Lava Hot, Warm and Cool. SS2 Bitmap A has one lava bitmap fill, and the Bitmap B style has one more. Those are what I found quickly, anyway, among the full-colour dungeon styles. It's also worth looking at the various stone textures in the same style pack as the lava fills, as some could be used as cooled lava too - or changed up to something hotter using some of the colour-changing Effects options, perhaps.

Ralf demonstrated exactly this, and the method to increase a river's size on an overland map, using the Pete Fenlon style, a couple of weeks ago on the YouTube live mapping stream. It starts around 19 minutes in here.

Thinking further about this, it occurred to me it might be helpful to provide a list of manufacturers that produce, or have produced, downloadable card and paper models, with website links. I'll not pretend this will be fully comprehensive, but it may give some more precise pointers than simply advising people to go and hunt through the OBS sites and CWF. Where not noted, the scale is generally the "standard" 28 mm-32 mm used for most fantasy and science-fiction gaming (which of course isn't a true scale at all, but what can you do?).

Antohammer the Lonely Wargamer: Mostly 2D standee paper minis, with some 2D, 2.5D and occasionally 3D models as well (of terrain features, smaller structures and a few vehicles), fantasy and historical.

Arid Hills Gaming: A limited range of 2D, 2.5D and 3D fantasy and science-fiction gaming terrain and props (e.g. for dungeons and graveyards). Manufacturer has now though switched to 3D printer files only.

Avalon Game Company: Mostly paper minis (plus a massive collection of written RPG accessories, gaming floor tiles, tabletop print-and-play games and accessories), with a limited range of fantasy 2D and 3D scenery, e.g. for dungeons.

Black-Ronin: A small number of 15mm-18mm scale 3D exterior modern buildings and structures, and 2D floorplan textures, intended for historical wargames.

Crooked Staff Publishing: A VAST and increasing range of Pay What You Want texture packs for creating your own scenery. The guy who is the company, Kristian Richards, also produces regular short YouTube videos (59 so far!) on using these to make 2D, 2.5D and 3D models (attaching the texture to various types of card and foamcore first, very often), and has an enthusiastic Discord channel. Although not specific models as such, the PDF file textures could be easily converted and transplanted for personal use in CC3+ to draw specific models using them in Dioramas 3, for instance. The videos are especially to be recommended for new card model builders, and mappers particularly may care to view the, currently 4, "Tiny Terrain" videos, which are in essence 3D hexmaps!

DarekPages: A small, occasionally growing, range of 3D terrain models, some vehicles and 2D minis, for near-future/science-fiction settings (although some items will work for fantasy too), with comprehensive photographic instructions.

Dave Graffam Models: A huge, still growing, range of 3D, mostly exterior-only, models for fantasy and science-fiction settings, with 2D ground tiles as well. Instructions provided with each kit, many of which make heavy use of the PDF layers facility, so each model can be built in a variety of appearances.

Eddnic: All-free, more-or-less unique 3D paper minis, and some 2.5D and 3D fantasy prop models (HeroQuest-style, after the 1980s fantasy boardgame of that name). Not for beginners, as some can be very difficult to make, there are NO instructions, and searching through to find what might be of interest is a challenge in itself (as it's purely a blog site), but the models are often astonishing and - as mentioned - free + unique!

Epic Wargaming also known as Print and Play Fantasy: Primarily wargame-style 2D fantasy standee minis, but there are a couple of 3D models as well, notably a castle on the Wargame Vault site. A major website failure three years back has meant the ranges are still incomplete on the new site, although new minis are produced from time to time. Many of the minis are free, though some are Patreon-only items now.

Fat Dragon Games: A large range of mostly 3D buildings and terrain (for possibly the greatest number of biomes available anywhere in papercrafting), the later models often making use of the PDF layers feature to extend the options for how the final models can appear. Mostly fantasy structures, with some science-fiction, although the natural landscape terrain has many more uses. The owner has switched to 3D printed models only now, so the existing paper-model range is unlikely to expand further.

Finger and Toe Models: A large range of 3D building, structure and vehicle models for fantasy, historical and science-fiction settings. Mostly exterior-only models, and provided with illustrated instructions.

Haunted Dimensions: A host of horror-themed, free, 3D models, games and some minis. The models are chiefly exterior-only, though they do include the Bates and Amityville houses from their respective movies.

Helion & Company: Their Paper Soldiers range of hardcopy and PDF books each contain complete pairs of historical wargame armies of minis, basic rules and usually some 2.5D or 3D terrain features and miniatures, and come with full instructions. Two sets, "European Buildings" and "Castle Assault", are especially heavy on the 3D buildings side!

Hotz Stuff: A range of 1/300 scale historical naval wargame minis, including 3D ship and building/structure models, plus a range of 30 mm (1/60 scale) Wild West buildings and structures. No new items in more than a decade, however.

Kingsway Models: Mostly hardcopy-only OO-scale (roughly 1/76 scale) historical British railway model structures and buildings, with a few free downloadable PDF items. Some 1/43 scale (O gauge) items also available. Print quality on the hardcopy items is often not as good as you would hope, from personal experience, and this is true also of the PDFs.

Lord ZseZse Works: A range of 3D models (as well as lots of 2D ground-tile flats), primarily for fantasy settings, and including some terrain features as well as structures. Also a few 3D vehicles (historical Russian tanks). Unfortunately, after a very successful Elven Papercraft KickStarter campaign in 2014, the company ran into problems delivering all they'd hoped to from that, and although all their models remain available for purchase, no new models are likely, as the owners split-up in 2017.

Mystic Mountain Productions: A modest range of fantasy 3D buildings, mostly exteriors, though some with internal 2D floor plans as well, with comprehensive photographic instructions. Often makes use of PDF layers to enhance the final appearance options. No new models since 2017, however.

Okumarts Games: A large range of mostly 2D standee paper minis, but also produces some 2D, 2.5D and 3D models (dungeons especially in the latter type), mostly for fantasy and science-fiction settings, also some historical minis. Detailed photographic instructions are provided for the models, and the PDFs nearly always make much use of the PDF layers facility.

One Monk (also known as Mayhem in Paper) : Although One Monk produces chiefly 2D standee fantasy minis and a few 3D vehicles, their main website also hosts a huge repository for many free minis and models created over the years by the papercrafting community, in recent years via the Cardboard Warriors Forum's "Monthly Hoard" system, or produced by individuals outside that.

Papercraft Dungeon also known as Kev's Lounge: A range of mostly 2D paper standee fantasy minis, with a small range of 3D structures, the buildings coming with full external and internal artwork. The build mechanics can be complex for the structures, and although photographic instructions are provided, they work better for those with plenty of paper model-making experience. Tending to concentrate chiefly on standee minis only in recent years, however. In addition, not all the models are available via the OneBookShelf sites (the link above), and the owner's site, Papercraft Dungeon, while allowing easy paid-for and free downloads, will only let you download each item in your account a limited number of times - so make plenty of back-up copies!

Papermau: An extensive, very long-running blog, which serves chiefly to highlight some of the many paper model creations freely available across the Internet down the years. The blog's author also makes new, usually 3D exterior-only, models from time to time as well. Being Brazil-based, a few of the blog posts in the past two years have become rather politicised, which may be something to be aware of.

Paper Realms: A large and growing range of 3D exterior buildings, 2.5D/3D subterranean and ruin models for historical and fantasy settings, with some props sets and ground tiles, and some overground 3D terrain models, including options via PDF layers, and instructions.

Papier Schnitzel: A substantial and growing range of mostly historical 3D model structures and ships (Dark Age Europe and Medieval Asia, primarily), usually with full exteriors and interiors, making extensive use of PDF layers, and provided with detailed, photographic instructions.

PERMES: Chiefly a 2D standee minis producer (vast range; historical, fantasy and science-fiction), some of the sets do come with pieces of 2D or 2.5D terrain as well, and a few packs are chiefly of this sort. Instructions are not always provided, so some experience with paper modelling is necessary to get the most from these models.

Ravensblight: The "Toyshop" section has a substantial range of free horror-themed 3D exterior-only buildings, games and vehicles, including full-sized novelty items. Commonly added-to around Hallowe'en in most years, in some cases with RPG/story notes as well, plus separate PDFs with instructions.

Reviresco Tin-Soldier: A small range of mostly exterior 3D model vehicles, structures and buildings, making use of PDF layers to swap things around at times, and with useful, illustrated instructions.

Scalescenes: A growing range of British model railway structures, buildings and some vehicles, available in OO (1/72) and N (1/148) scales and with different exterior texture options (though only one scale, and one texture option, is provided in each paid-for downloadable model). Illustrated instructions come with each kit. Look out too for the free downloadable PDF scale rulers!

Stoelzel's Structures: A large range of highly detailed 3D models with full interiors and exteriors, often with props, and comprehensive instructions, suitable for near-modern and horror settings particularly, with some fantasy items (such as caves and dungeons). PDF layers are not used, so there are commonly huge numbers of pages per PDF, which can make it difficult to keep track of what to print when there are options available. Also relies on the use of foamcore to retain the correct wall thicknesses, so the walls are simply covers for that.

Tinkering Tom: A small selection of 3D building models, fantasy-historical in nature, complete with illustrated instructions.

Wordsworth Model Railway: A substantial range of British OO scale 3D exterior railway model structures and buildings, all free. Also a YouTube channel with a huge number of construction videos. Video 92 is recommended for beginners by the company, as a 10-minute general introduction to making card buildings.

World Works Games: A large range of 3D fantasy, horror and science-fiction model structures, buildings and some vehicles. Unfortunately, the range is no longer supported, so is unlikely to further expand. In addition, the kits are all available only through the company's own website, and it too is not regularly maintained, so in recent years, it has been frequently, and unpredictably, offline for unexplained reasons. As only a limited number of downloads are available from each purchase, be sure to make plenty of extra back-up copies of anything purchased from the site.

Realistically, and much as Sue already said, if you're aiming for a hand-done pen and wash style illustration, it should look like a watercolour painting, where the wash sometimes covers the line, sometimes runs short of it. There isn't a voting option for that, and I really don't see this as an "either or" choice. So sometimes that'd be "A", sometimes "B", but more often a mix of both, with some additional overlap too.