Wow, that's some dedication to try and reduce the blockiness of foamboard, looking forward to see how you get it done. One alternative was to use your shape on mounting board and then apply Air Drying clay to both sides and sand it back - proabably a little more effort though but you can results like this guys:



Here's his step-by-step

[url]http://daboyzateam.proboards.com/index.cgi?board=painting&action=display&thread=339 2[/url]