There is only so much you can learn about a subject by reading up on it or watching YouTube videos. So once I actually started 3D printing sample sets of Dragonlock and True Tiles, I learned a lot that these sources hadn't taught me.

First, the cost estimate I had for 20 to 40 cents per tile is a bit too optimistic. A simple Dragonlock tile with one wall weighs already 20 grams, at medium quality with just 10% infill. While you theoretically can get 3D printer filament for 1 cent per gram ($10 per kg), that would be very shitty material that I wouldn't recommend using. So the higher end of the estimate, 40 cents per tile, is actually the lower end of what I think printing tiles costs: 40 to 80 cents per tile for the Dragonlock system.

However I won't use Dragonlock. I don't like the thick, high walls. I can see how those look great on a photo of a large dungeon you assembled. But for actually playing the high walls block the view on the figurines. And they take up half a space, so you end up with a room lined with half spaces on which you can't really put figurines. I much prefer the True Tiles system, which has low walls, and squares of 1.25", of which the walls take only 0.25", so there is still room for a miniature next to the wall or even in the corners. That also makes the tiles lighter, which lowers both printing cost and time.

The locking system of the Dragonlock system also turned out to be not optimal: You need to print tiles with rectangular holes in the side. Which means that the top of the hole isn't supported, so it sagged and I needed to clear the holes manually to be able to fit a clip in. The True Tiles sample set prints tiles that are very flat, and can then be glued on a OpenLOCK compatible base. The holes on the base are open towards the top, so you don't get the sagging problem.

But then I bought several sets of True Tiles, and found out that the sample set isn't representative of the system: Not all the tiles in the sets are so thin that they can be glued on an OpenLOCK base. For example the tiles that have both floor and water use a height difference of a few millimeters to indicate which surface is the water. And so the tiles of that set already have a base which is as thick as a Dragonlock or OpenLOCK base. You could still glue another base under it, but then your tiles become very heavy.

So I wasn't really happy with any of the locking systems. But then I thought that maybe I don't need one: Those 2 x 2 squares (2.5" x 2.5" in the case of True Tiles) are solid enough to not move around a lot when assembled without locks. I'm too lazy to drill holes in all tiles to add a little magnet, which is a fancy method recommended on YouTube. So I think I'll just use them without any locking system at all. Which means having to transport a dungeon as a pile of tiles and assembling it on the spot, but that has advantages as well as disadvantages, so I am okay with that. And I will use the True Tiles with the thicker base, both for stability, and to enable me using the water tiles.

The one downside of that decision is that even a True Tile with the low wall gains some weight when printed with a thicker base. The thin tiles are just 8 grams, but the thick base tiles end up at twice that, 16 grams. Only 20% less than the Dragonlock tiles. And I am using a high end material which costs 4 cents per gram. It is the Z-ABS from Zortrax, the company that made my printer. Not cheap, but really nice quality, and there are standardized settings for the Zortrax material in the slicer software, so I don't need to fiddle around with the parameters. Also the thicker base and my not-so-ugly print settings mean that the print job of 4 single-wall tiles I started this morning takes 9 hours to print. In other words I can do two print jobs like that per day, one while I am at work, the other at night. It'll take me some weeks and some spools of material before I have a nice large collection.

My only remaining problem is color. I'm printing in "warm grey", which looks nice enough for stone floors and tiles. Doors don't look so well in grey, but they are clip-on, so I can print them in another color. Where it gets tricky is the water tiles, which have both stone and water on them. My 3D printer in mono-color, so they are going to be all grey. The obvious solution is to paint the water part blue with some acrylic paint. But that is something I will have to learn and acquire the materials for, I never painted miniatures before.