Guy at the hardware store in Dayton said cardboard is just free foam, and my Reinhardt shoulders proved him right
Was in line at a True Value in Dayton picking up wood glue and overheard a guy tell his kid that corrugated cardboard is basically free foam board if you seal it right. Stuck in my head. Went home, cut up two Amazon boxes, layered them with wood glue in a cross grain pattern, and it dried stiffer than the $14 foam I bought for my last build. Coated it in three thin layers of Mod Podge, then plasti dip. Came out to about $4 total for a set of shoulders that were quoted at $50 online. Weight is only slightly heavier than foam and honestly it holds paint better. Curious if anyone else has tried the cross grain trick or if there is a better cheap sealer than Mod Podge.