Lightweight paint poles make great push up masts for field day or backpacker contest type activity. The poles generally have a threaded end and are a variety of different threads from ACME to ISO and tapered in between.
This adapater is for my lightweight 2m beam that uses a 20mm x 20mm box section (thin walled) beam and plastic spreaders. The adapter screws onto the opd of a Harris 5m paint pole that I got from B&Q but should fit just about anything.
There is a print file on Thingiverse but I will tinker with the design but for now the WIP is, as always, held on my OnShape account. There will be no drawings held here, all copies will be on Onshape.