Strongback

First was the side pieces which were in two pieces each, joined with blocks inside and out and four 8mm bolts/glue per side. 

Then I clamped them close together and marked out all the places for the cross members for strength, marked the position of the legs and also the frames (measurements adjusted for my stretch).

Then I clamped all the cross members in place and screwed them into the sides with 70mm tech screws (two per side). This gave me the basic frame. 

Then I cut 10 legs 400mm long, and while upside down clamped them in place four at a time. I then checked the level each way including the ones already done, sideways, horizontally and also diagonal. I also checked each leg for level. Then I crossed my fingers and bolted them all to the sides with two bolts per leg.

Once I had finished all the legs, I flipped it over. 

A further two tech screws were put in per leg where the leg was underneath the cross pieces. This was at each end, and one of the legs in the middle.   The final step was a 9mm ply end piece glued and screwed to the legs each end, the sides and the cross piece.  There is one of these on each side at each end to provide bracing.

From the side below, four tech screws 70mm long from the top, two 8mm bolts from the side through the leg and side piece, plus the ply and screws/glue from the front.  Hopefully strong enough....

The final check was level along each of the sides at various points, then each of cross braces. Below is the result, with help from my assistant (and the blokes who laid the level concrete slab for my shed, I owe them a beer).

Side pieces:

Cross pieces:

To give me an excuse for a beer, I stood up frame 3 ( it is too low but looks the part!).

Onwards to standing up the frames, have to borrow a laser level.