Sitting around recovering, I'm thinking would you like to see a way to make masters with everyday materials.
I used this method before I had access to any Ureol. It's not the easiest, but if you want to get to a shell without doing the slush stage, this is the way to do it.
I made FPF's first three masters this way..the P6 Rover racer, the Lola T70 and the Lola Mk 4 F1 car.
It's basically a case of making a balsa sub carcase that looks vaguely the right shape. Just roughly transfer your plans to the balsa (say 1/4" sheet), less about 3/16" all over. This will be the filler. Car body filler..Bondo, P38, Tetrosyl, etc. get the easy sanding sort. A small pot is sufficient for one 1/32nd scale car. When it's all shaped up, you dig out the balsa and you have a filler shell, which you can then fill, or thin and add chassis mounts to.
Now filler has three states. 1) liquid, as mixed.
2) cheesy, starting to set
3) gone off.
Slar on the stage 1) stuff to the thickness if possible, otherwise do it in 2 layers.
It'll likely be a bit spikey by now, so, while it's still in stage 2), knife off any silly excesses. It really is like a firm cheese. Slice off excess, but once it feels a bit too firm, stop. Keep this up till you have enough filler loaded on the balsa carcase to enable the final shape to be made from it.
Off to take a picture of the one I've had kicking around for years! I also made Alfa GTV and FIAT 500 at the time, but someone else did those.
You'll need coarse files, a 1/2" chisel (sharp) and a few bits of coarsish sandpaper to start shaping. Anything finer will clog annoyingly. You will still ideally have a sheet of file carding handy to clear out your files regularly.
If you don't like dust, this ain't for you!
Cheers,
Martin