Photo 1, Cut from a 3mm sheet of plastic i got from the “help yourself bin” at Homebase.

Photo 2, 3mm is really quite stiff so the ratchet strap took most of the strain.

Photo 3, Speed welding plastic. I got the info here;
https://en.wikipedia.org/wiki/Plastic_welding & used a cheap soldering iron.
Thin strips of plastic were cut & used as welding rods to add to the mix. Important point is it must be the same plastic. Drag the iron & push it along with the rod, everything will melt & mix. You can pretty the weld up with the iron when finished.

Photo 4, I ran the tip of the iron without any rods along the outer seam which made it look neat. I purposely left an overhang with the intention of filing it down but it looks OK as is.

Photo 5, Just needs a spray (probably black) & some stickers.
Didn’t cost me anything apart from a cut finger 🙁
The weld is surprisingly strong. I thought it would snap straight off when the ratchet strap was removed but it holds fast.