Here's a shit-simple mould with its not-so-crappy result.
Had some excess polyurethane and a mould that was sealed and I had forgotten what it was, so I poured some of the excess plastic into that, turned out to be the wings for the WHFB Warhawk I made a mould of to stop me from becoming crazy with rage when the superheavy wings fell of all the time. I have since learned better pinning methods :)
Yeah, the Khandish Charioteers are going forward - a while ago I ordered a blister of Khandish Warriors to replace the old plastic copies I did - they looked okay, but the originals in white metal should be better now that I actually put some more serious work into the chariots. BTW, the Khandish Warrior mould(s) from GW really seems to getting old, the white-metal ones had as many flaws as a so called Finecast model...
How to do it
Take a 64 mm base, a piece of arts cardboard (will not burst into flames when hardening the super sculpey) and some super sculpey. Make a ring, flatten it somewhat so it almost looks like a ready mould. Then press the 64mm base into it (use talc as a release... release agent?) and remove it and fix it up a bit. Harden it with a heat gun or put it in your oven (read the label of your Super Sculpey(tm) to get the correct temp). Done. Then pour your favorite polyurethane into it. Let it almost harden and then remove. Use a release agent if you like - I used violence and the mould will probably hold for another 5 or 6 bases.
Normally when I try to take income from GW I make better moulds, for example the mould of the Axemen of Lossarnach - which gave me a really nice formation of four companies, but for simple crap like a base, one could skip almost all difficult and careful steps (in mould making AND when casting) and just produce four or five of these flippers, if you like. If you wonder why my language is strong, then it is because I've been training the same time as I have inhaled poisonous fumes so the testosterone levels are whooooooaaaarrwwww! Fuck yeah! I am currently screaming at my biceps as I'm writing! Wööööööööööh! I'M WRITING THE FUCK OUT OF THIS BLOG!!! WOOHOOO!