AP Photoplastics is the source for many products that we use in analog photography. In fact they make a lot of the film packaging that is used fro various brands of film.
The tanks are made in two versions, and so are the reels. I find the "classic version is handier for 135 but the new version which for some reason they call "compact" is a big help with 120.
http://www.apphoto.es/ap_products/docs/eng/tanques_espirales.htm
Freestyle, Frugal Photographer and others sell these. Last time I checked Frugal had a close-out on the "classic" style reels.
if you look though the AP site you will probably see at least a few items in your own darkroom collection.