I have not tried this product, but I do use something similar it's call Sculptamold. The name of the company that makes it is Amaco. It mixes with water (2 parts sculptamold 1 part water) I used it to make a wing fillet on a T/F mustang and it worked great, very light weight. It takes about 10 hours to cure for sanding. The web site is www.amaco.com and it costs about $7.00 for 3 lbs. I bought mine at Hobbytown USA