How to fix glass kaleidoscope inside cardboard tube

Question

I have a maker/craft project making a kaleidoscope out of three mirrors and a badminton shuttlecock tube (sawn in half).

This will be a project for a class of school kids aged 8-12, so we'll have to teach them to make the item by hand.

Is hot glue (handled by teachers only) the best way to secure the glass triangle inside the tube, or is there a better, long-lasting secure way to fix it in place without risk of dropping out from the tube after several months? Kids safety in mind here.

3x mirrors measuring 2in x 6in each

Sawn shuttlecock tube length is just under 8 inches

Answer 1

If the size of the mirrors is such, that it's already (sort-of) tight fitting in the tube, then you don't need much force to keep things in place. You may consider a kneadable adhesive like blu-tack.
An Internet search also leads to someone mentioning dimensional glue dots. Glue Dots are a name brand adhesive, sort of like stickers except the stickers are double-sided tape pieces, but also refers generically to similar products.

If all else fails, you can stick to the hot glue.

Answer 2

Considering you're working with glass, have you thought about using window putty to secure the mirrors in the tube? Children that age should be sensible enough to work with it safely (i.e. they're not likely to eat it etc.)

You can see a guide for using it to secure a window here: https://snapguide.com/guides/use-putty-for-window-glazing-simple-guide/

Once dried it should last a long time, certainly until the kids are grown up!