Make your own parallel cramps
a chunkier version of something like this
[video]https://www.youtube.com/watch?v=vSwlM7cf6mo[/video]
Normally if you were glue strips together you’d want the faces you were gluing to be planed smooth otherwise its only the lumps and bumps on each face that would be glued together and most of your joint would be full of air.
But if you use polyurethane wood glue (gorilla glue or joiners mate) it foams and fills any gaps so its better for gluing rougher surfaces. You need to be fast though and the foaming can push everything apart before you’ve got it clamped up.
It can get messy too. Top tip – if you get polyurethane on your skin wash it off with WD40 fast before it sets otherwise you’ve pretty much got a glue tattoo for next week or so.