This is the foambord I use for my sculptingstands. This can be baked with the sculpture in the oven. This will give you a smooth plain surface to sculpt on.
Kapa line 3mm foamboard 3x130x130mm (2pcs) — BeeSPuttY
Balsafoam - The Compleat Sculptor
Balsa wood block 30x30x50mm — BeeSPuttY
KAPA® line, lightweight foam board in 3 - 20mm
KAPA® boards
Union : Foam board : 3mm : A3
UCreate Foam Board, White, 22 x 28, 5 Sheets : Office Products
KAPA®-Mount - Fancy Papers
UCreate Foam Board, White, 22 x 28, 5 Sheets : Office Products
Foamboard hanseungjs