How to glue up a Maloof seat?

Jalen is gluing up the seat on his Maloof chair but when we clamped the prototype it created gaps as we clamped the sides with the 3 degree angle on sides of the boards. We clamped it to the workbench and fixed most of it but it seems there may be a better way.

Charles Brooks talks about a clamping jig he uses but I can’t find any details on it. The second time we made maple runners for it to set on and them cut shims the height of the offset between the two outside boards and the middle board. We then clamped them down before applying a lot of pressure from the side.

This worked better but I am not sure this is the best solution. Does anyone have any suggestions on a better way to do this?

-- Jeff Waggoner, http://www.planeoldwood.com https://www.facebook.com/pages/Plane-Old-Wood