I found finding a battery (ie laptop battery) to power an A600/CD32 board very difficult so gave up.
Also it's a tough choice...horribly restricted CD32 motherboard...or waste of time ECS non AGA A600 motherboard.
Short of taking a hacksaw to an A1200 motherboard and spending 2 years patching up the pieces with solder and wires this isn't really going to happen. Minimig was being put into a tiny case with a PS1 screen a while ago I remember...this also isn't really ideal.
Shame...if the A1200 board was just that little bit less wide it could make a nice 17" 'laptop' I think and would then fit into a nice existing laptop chassis with some modification but it just isn't slim enough...ho hum