Here the back standard has been assembled. You can see quite clearly how roughly the pieces have been cut. If I was doing it again I’d probably take a lot more care - and maybe use a router table like I did when I made the toy fire engine for Benjamin. However it does show that camera construction doesn’t have to be complicated.
The hole in the bottom piece is to take the back end of the rail. Fixing it like this did mean I couldn’t have any movements on the back standard - but it did keep the construction simple.