Progress today
Routed the two slanted back pieces. First time using this kind of router.
There are several fillets to make and I used square and triangular standard parts to make what I needed.

Added the two braces as per building instructions, this is looking down in the pipe with the front facing down

Then I screwed and glued the corner fillets in place, while this is setting I am taking a break to be sharp before the critical assembly of those tricky back pieces.

The pieces  will be predrilled and dry assembled once to make sure that all meet up resonably well.