On Mar 26, 1:29*pm, Robin wrote:
I'm working on a little project (a spotlight) that is basically a bit
of aluminium tubing, 50mm ID, 5mm wall thickness. I was wondering the
best way to close the end of the tube

c) Cut a chamfered plug and bond it to the tube - not sure what
adhesive to use

How about solder? With the right fluxes and aluminum solder you
get a good tight join. Drawn plug of soft aluminum would be
suitable, too.