It will in fact leave marks on the sculpt. I left the helmet on mine for a few weeks and it put indentations in the face. I had to buy a new sculpt on eBay as a replacement.I'm curious if anybody has any insight on whether or not displaying these with the helmet on long term damages the sculpt? I have been too afraid to do it myself and thus far I have been too lazy to try to customize a knockoff dummy sculpt.