So, you have more time than money to pay for Dragon Forge Attack Bike bases, or you're just too stubborn to pay $7.00 for one base, no matter how nice it looks? Or you think you can do better? Or something?
Well here's what you need:
a 60mm/dread size beveled base
a 40mm or 50mm square base - I used a 50mm base.
Cut both bases in half, using a sharp hobby knife. Trim the drill guide holes on the bottom of the round base if needed.
Trim the outside corners of each half of the the square base so that the corners mate up flush with the round base, like so:
Once it all fits, then glue it!
Once the glue has set, cover the base with plasticard. If you're making it for a thunder fire, I'd recommend thicker plasticard as it lends the base more structure, which you need for this heavier model. I even went so far as to brace the bottom of the base with ribs made from spare sprues. You can use just ordinary plasticard, of course, but you can also dress it up like I did:
I'm going to add more texture and even more fancy crap to it. Now I just need a casting kit to cast my own resin bases... :)
And here is the base, painted and completed.