I don't know who needs to hear this (the answer is probably no one Cameron) but the easiest way to close the end of IC tubes like this is to just take an xacto knife and make a tiny cut like this. Then you can press in or out the corner to make a toggleable door, no keeping track of little plastic pegs or tape required
@old_angry_queer
I used to use drawing pins.
At one point the workshop had a whole bunch of weird small batteries shaped like baby spam tins in similar tubes. Eyebrows raised when some bright spark put a multimeter across one of said packages and measured about 250V.
