I ordered aluminium tubes for the main mast, yard and battens a couple of days ago. They arrived today. We’ve got:

Amazingly the topmast/strengthener actually fits perfectly inside the main tube!

TBH I wasn’t expecting this to fit due to the tolerances on the tubes, but I figured that it was worth ordering as it wasn’t expensive and I could use the tube elsewhere. Now need to work out how to put it all together. I may still add wood to the mast – we’ll see.