Here's after the glazing putty has been sanded off
Here's a close-up of the glazing putty filling small voids in the fiberglass filler
Here is the rotating painting stand. It consists of two 2'x2'x3/4" pieces of plywood, two 9"x9"x3/4" pieces of plywood, a 1 1/4" pipe flange, a 1" pipe flange, a 1 1/4" x 3' piece of galvanized pipe, a 1" x 3' piece of galvanized pipe, glue, wood screws and eight 1/4" x 1 1/2" lag bolts.
The small pieces of plywood are centered then glued and screwed to the larger pieces of plywood.
The pipe flanges are attached to the small pieces of plywood with lag bolts. That completes the assembly.
To use the stand, screw each piece of pipe into it's corresponding flange. Slide the 1" pipe inside the 1 1/4" pipe and the stand is ready to use. The 1" pipe fits snug enough inside the 1 1/4" pipe that there is no slop or side play but loose enough to turn easily.
When you're done, pull the top piece out of the bottom piece, unscrew the pieces of pipe and put it away.
Here it is in pictures
Broke back down and ready to be put away
To change the height of the stand, just get longer or shorter pieces of pipe. Not enough work surface? Use bigger pieces of plywood. The instructions I found for this stand used 48" round pieces of plywood.
I'll round the edges off later on.