I thought about blue tape -- I already keep a roll of it in my sewing kit. My preference though would be to stick it on the inside of the cone and then I think you still have the possibility of the thread looping over the spool and coming off. Do you just put a piece down on the outside or peel back a corner or anything for easier take off?
The idea with the hairbands is that they don't stick to the hair (so much) and so will be easy to pull on/off the spools. The reality is that this is enough thread for the rest of my sewing life and maybe something like the press and seal and pretend that they are just all new until I want that particular one might be good. Had a friend who was crazy good at doing everything that couldn't be done with duct tape with press and seal!
The netting, I think I see that in the thrift stores sometimes -- it is green? Does it come in clear or other colors??