I came across this topic whilst disposing of a spam post. Having just changed our electric toothbrushes and kept the originals (just in case they come in useful!) I have converted one similarly to as described above except that I epoxied a small cube of wood to the head and used double sided tape to attach a square of aprasive paper – it works really well if tou want to do some delicate mechanical sanding. Easy to put a new pad of abrasive paper on too by simply peeling off the old one first.
If tou don't have a spare toothbrush then Wilko sell an excellent one powered by 2AA batteries for just £4.50 and spare heads are cheap too:
**LINK**
Colin
Edited By Colin Bishop on 28/12/2018 16:05:42