Maybe this should go in the "Way off Topic" thread, but here goes anyway. I'm thinking about trying to use bondo to repair a partially rotted joist in the patio cover. If I have to replace the joist, I'm looking at major rebuild. If I can use bondo, I am hoping to be able to build a form out of plywood (or some other material) and fill it with bondo. However, I'm afraid that the bondo is going to bond to the plywood form; then I'm SOL as far as removing the form and shaping/finishing the bondo. Has anyone tried this, or is there a better material to use for a form that won't stick to the bondo?