With regard to adapters that will allow you to use 26650 cells in a 32650 light, almost all of the USA national craft stores (Michael's, Hobby Lobby, Blick's for example) carry flexible foam craft sheets. These foam sheets are thin, generally about 1/16th of an inch (2mm), and are easily cut with a scissor or knife to whatever length and width you require. The foam is most commonly available in 8x11" or 11x17" sheets. Simply cut the sheet to slightly less than the length of your battery so that the electrical terminals are able to maintain contact, then wrap the trimmed foam around the cell until the "extra" space between the cell and the battery tube is filled. The foam is non-conducting, and eliminates battery rattle. It's also dirt cheap, and one sheet can make multiple adapters. The foam is ultra lightweight; it comes in a variety of colors including discrete grays, charcoal, and black. That noted, electric green and safety orange are my favorites: it's hard to lose one of those when changing cells after dark.
