After accumulating several used rolls of 3n3 filament, I thought of making a rotating sample book with them.
The wheels go between rolls and one of t...hem is for the stop, which is screwed to the roll (so the top ring with key rings and everything is not stolen).
And the cover with card holder goes over the screws, stuck to the pipe.
I used a 19mm pipe, which dances on the base and cover, but then I glued it with ordinary glue and it held quite well.