Stick sandpaper to cutoff pieces of PVC water pipe with spray-on adhesive and you'll be able to sand concave curves to perfection. PVC pipe is labeled by inside diameter; here's an index for the outside diameter of useful pipe sizes.

• 1/2-in. i.d. = 7/8-in. o.d.
• 3/4-in. i.d. = 1-in. o.d.
• 1-in. i.d. = 1-1/4-in. o.d.
• 1-1/4-in. i.d. = 1-5/8-in. o.d.
• 1-1/2-in. i.d. = 1-7/8-in. o.d.

To apply sandpaper to the pipe, spray both the paper and the pipe with a generous layer of adhesive. Let both surfaces dry several minutes before joining them. Use two grits on each pipe—80-grit for sculpting a precise radius, and 100- or 120-grit for finish sanding. When the sandpaper's worn out, just pull it off, spray fresh adhesive on a new strip and go back to having fun.