Van windsurf rack/1 inch couplings

Useful couplings to construct a variety of light weight frames using 1" (25.4mm) square Aluminium extrusion.  You can buy these at a hardware store, except when you can't.  There are also shapes you can't buy.   These parts are hammer fit and don't fall apart.

Was building a rack to hold all my windsurf gear (which is why it is entry in transport comp) in the van using 1" Aluminium square extrusion and plastic couplings.  Thanks to all this supply chain disruption (compounded where I live by a once in 300 year flood cutting the train line to West Australia) the plastic couplings were out of stock. There was also shapes (like a basic straight coupling) that didn't exist.   I searched Prusa, thingiverse etc thinking someone had designed these already and was surprised nobody had.   So I quickly designed these to finish my rack.  They were printed in PETG and are stronger and cheaper than the store bought ones.  

To eliminate the need for supports, all parts except the end caps and pin are split.  They are joined by either printed pins, or, 8mm wooden dowels.   I had a bunch of these dowels sitting around (8mm x 30mm) which I cut in two.   Easiest to hammer the whole dowel into one side to make it easier to hold then cut the dowel in half to use in another hole). The second photo is supposed to illustrate the process if using dowels.  The dowels or pins are only needed to hold the parts whilst you hammer them into the extrusions.

I originally designed many more parts but then realised many different shapes can be realised with only a few parts.  i.e. a 5 Way coupling can be made with 2 x part 4 Way B etc etc.  If I've omitted to upload some combo, please put in comments.

If you make an error you just hammer the parts out again.  In the case of the straight sections, hold them with vice grips and hammer that to remove parts or punch from the opposite side.