Battery-powered toothbrushes don't fit in toothbrush holders and end up lying on a wet, messy countertop.
Mount neodymium (“rare earth”) magnets on a Corian mounting strip with Super Glue. Glue the strip to the wall with Super Glue or silicone caulk.
Tools and materials:
To make the mounting strip, cut a Corian threshold (available at tile stores and home centers) with a miter saw or jigsaw. Neodymium magnets are available from internet suppliers (search “neodymium magnets”). We used 1/2-in. x 2-in. x 1/8-in. magnets, grade N42 (the higher the grade, the stronger the magnet). You can double them up if you need more holding power.
Neodymium magnets are incredibly strong but break if handled roughly. Order several more than you need—shipping is expensive. Also, don't handle neodymium magnets if you wear a pacemaker, and never leave them next to your computer or credit card. For more safety information, search “neodymium magnet safety” on the internet.