Here's a technique I've used twice in the last three days.

I have a boat with a curved deck. I wanted to make some flat but movable, adjustable panels that fit snugly to the top of that deck. I'll put the raised oarlocks on top of those curved pieces in a later step.

So how do you make an 8" wide by 16" long by 3/4" thick Plascore rectangle that conforms to a curved surface?
..........Visqueen.

I put visqueen flat on the deck. Stretched it out tight and duct taped the edges. Then I put down some glass. Wet it out. Put the plascore down. Wet out the top of the plascore. Put down some more glass. Wet that out. Put one final layer of visqueen on top of the whole works. Put 1/4" plywood on top of that and then stacked a bunch of weight on top. What you get is similar to vacuum bagging: a tight layup with all the air squeezed out, with a glass-smooth surface when you're done.



===> a little more visqueen molding <===

For the topside on the mechanical vac bag, I've used stretch wrap, the stuff you use to palletize loads and it's worked like a champ and you can pull it real tight.