As well as the Prisma Megamix I've also recently added a Deneb. This now has a 32GB USB thumb connected to the internal port, there's just enough space between the port and the voodoo heatsink. I have drilled a space in the Voodoo's backplate to mount one of the other headers.
I don't have room to use the Prisma's pci backplane so I've mounted the breakout board on top of the soundblaster. The cables route behind the Mediator and out through the expansion port.
Deneb, ZorRam and Prisma
All PCI and Zorro 3 slots are full now. The fan pulls hot air away from the Voodoo 3 and the Sonnet.
Everything is flush so the case lid goes on ok.