Yet again I find myself with nice thick cardboard tubes. These are 16 3/8 x 3 (from packing film rolls). This time I must use them in a project. I’m thinking telescope. Where can I find 3” lens or mirror? I’m thinking I’ll make a refractor, a reflector, and a third thing
What interesting thing can I do with some strong cardboard tubing? Besides mail posters or build a telescope? I have 3 pieces between 2-3 feet each and 3” inner diameter. It was a single large 7 foot tube I broke up to recycle but now I feel like I should do something with them