So...a crazy idea. There are some pretty neat 6mm sci fi miniatures out there. Khurasan and onslaught miniatures (especially onslaught as they have a lot of 1:1 models that fit 40k and Grimdark aesthetics).
I also was reading up about pocket 40k - which is especially using the epic 6mm separately and running regular 40k or kill team.
Here was my thought: get some 6 mm figures for Grimdark Future firefight. Magnetize them and use those metal poker or domino containers as pack-and-play boards. The inside could be painted up one way and the outside another way.
I've currently got one container in the works with the outside bottom painted as a landscape scene. Magnetized some trees and hills. I have a few objectives in the works.
Purchased some soul-snatcher cult equivalents from Onslaught minis (their command packs are perfect) and some Stygian/dark elf raiders.
Soul-Snatcher cult is magnetized, primed and base coats are going on. The idea is you can easily bring this small kit with you. Rules can be folded up and placed inside along with small index card army sheets. The terrain and models are all magnetized so they go in the container. The lid goes on and bam - wargame in a box.
Metal lunchboxes would also totally work. I'll post pics if anyone is interested.
Here are the pics so far. I'll be adding more as the process continues. I didn't take pictures of priming and painting the metal tin. The last two pictures are of the tin tipped up on its short side just so you can see the "mat" ground. The last picture is of the inside with some magnetized terrain pieces inside for storage. I tend to deck out the inside two like the inside of some sci fi ship or bunker with platforms to stand on for more of a 3D setting. That's going be a bigger project.
The process: Find a metal container like a domino container or old metal lunch box. Prime. Several coats might be needed. Paint scenery. For outside scenes, a sponge with dark browns for the base, then layering to tans here and there with splotches of greens makes a great generic outside background. For terrain, foam cork is ripped or cut out into craggy shapes. A rare earth magnet is glued into a hole made in the bottom. Paint as you desire.
For the models, buy, prime and paint whatever brand you want. Magnetizing is going to be harder. Don't use rare earth. They are too strong. Instead, find some magnetic sheets or magnetic strips and use a hole punch to punch out circles which fit nicely on the bottom of the miniatures. Make sure the right pole is facing the right direction before gluing.
And that's it really. Everything is magnetized for easy storage inside the container and easy modular placement on the underside of the container which is now your game board. At 6mm you'll have to figure out converting movement and weapon rangers but there are plenty of guides for that.