The actual base is the same size as the GS one supplied with the scope ie. 50cm diameter. I made two disks this size out of doubled 12mm ply as I wanted the mass to be low and thought that if the base was solid at the bottom then the rest would be easy. Well it worked
I cut the lower disk into a triangular type shape on a whim that I would not bother with again. Now I have to ensure the ends that come in contact with the levelling circle are over the levelling circle feet or it wobbles. If I had left it a circle it would not matter a bit, well you live and learn.
I cut a circle out of the lower base to allow the attachment of the lazy susan bearing (from Carbatec). I also set up three magic sliders with milk jug washers to get the height right to stop the bearing allowing too much freedom. When bolted together this allows smooth movement with some resistance against the laminate surface glued onto the bottom of the upper disk.
The sides were simple and made out of 17mm ply. The cradle is 28.5cm across so I set the inside of the rocker box to 29cm. The side panels were set up to be as wide as possible while still sitting inside the base and looking "right" so they ended up 34cm wide. I routed the bearing surfaces, bearings were 150mm radius, allow for the 6mm teflon so the radius of the cutout was 156mm. I balanced the scope in the cradle, measured how far the scope stuck out from the bottom of the bearings, added 50mm to get the height of the sides to the bottom of the bearing.
These were simply screwed onto the base with some long screws, later I may make it collapsible with the use of piano hinges. The teflon pads were set to 35 degrees each side of the vertical and the scope went on beautifully.