Greetings. I thought I'd share a little bit about my process for basing these tiny titans. While much smaller than their 28mm cousins, these 8mm titans are still large enough to play with the bases. No need to simply glue them down to the supplied plastic base and leave it go. Have some fun!
For my collection, I have chosen Legios that all hail from Mars. I
pictured the titans striding across a broken martian landscape, rather
than in amongst the many Mechanicum facilities, if for no other reason
that they'd be constantly crushing stuff. I use cork board to represent
broken ground, selecting boards with cork pieces that are not too
coarse. You can get cork board on Amazon.com easy enough, and in various thicknesses.
It's super easy to break these up and I encourage the avid hobbyist to experiment with different shapes, and even stack pieces for elevation, though that requires planning ahead when building the model. Here, I've settled on a simple bit of cracked ground, maybe carved by an ancient martian river. Adding a few bits of Titanicus terrain (or something similarly scaled to 8mm), give a bit of narrative to the base and will provide some visual interest that helps communicate the towering scale of the titans.
I like to keep the legs around for a reference while I'm modelling a base to be sure everything will fit and look good when I'm done gluing things down. For cork, I generally use wood glue which I feel has a bit better grip and longevity over standard white (PVA) glue. I don't like super glue for this as I often move things around a bit and the longer setting time of a white or wood glue doesn't get in the way there. Also, while the glue is still not set, I sprinkle some of my mixed railroad ballast on it to give texture to exposed bits of the plastic base not covered by cork.
My last step is to use Vallejo Black Lava to texture the flat surfaces of the cork, and cover up its obvious texture and "corkiness". I hold the titan's feet in place and paint the gloppy black lava around the feet, trying to not get much on the model. It wipes off before dry with some water on a wet paper towel, though, so no worries. This approach leaves a good smooth surface to glue the titan to once the project is finished. We want these huge engines to appear sunk into the ground, not floating over it, after all.
On other bases, I have also used GW texture paints that crack when dry so simulate dry river beds and other parched ground that isn't so rocky. And that's that! You can really go free and crazy with your imagination here. Search the web to find many many examples. I hope this simple base sparks your own creativity for your projects. Hopefully we'll see some paint on this Warbringer before too long.
Stay safe out there.
Cheers and Happy Gaming!