I think a bottom will be necessary to get these to sell. The tracks, barrels, and pins that support and hold the pcb should be very universal between G80-3XXX variants. But G80-3XXX, G81-3XXX, and maybe 1XXX variants would be different from one another (I've never owned a 1XXX so I don't know about those). Not many people like G81's, and 1XXX are rare, so you don't necessarily have to support those. A universal G80-3XXX case would be my recommendation to make. If there is enough actual paying interest in winkeyless, then that option could be added as well.