After three months of layering paper and paint, my square piece is finally ready to go, so I cut away all the excess paper/paint and prepped it for sanding. Here you can see the layers (approximately 50 in this piece) along the side as I trimmed the edges before sanding:
And again, as I cut it down to the frame with my box cutter:
Here it is after an hour of power-sanding the surface with various grades of paper:
The colorful, diagonal patch is an experiment that I embedded within the upper layers, and I'm glad it stayed intact and came through so nicely. Now it's time to start working deeper, carving in, adding and subtracting, and see what I can really do with the piece.