The first stage is to bond one of the side pieces to the main frame.
Satisfyingly sides and the frames match up perfectly for height at the top and bottom edges.
I repeat the process on the other side and then slip in the two hopper ends.
And even more pleasingly the angled lip mates quite neatly too.
I think I'm pretty satisfied with that, so I shall crack on with making the masters for more of the detailed bits now.