I have been thinking of a dome for some while and have dithered between Segment and Geo. I also wanted to utilise the ease use and strength of multi wall polycarbonate sheet.

Using the cheap greenhouse replacement glazing from screw fix I built this model (75cm dia) Segments are glued but the straight section joined using half I beam section. (two Ls back to front). Using the metal beam section has worked really well. Centre sections come out. I have bought mini magnets and slipped them between the poly walls to hold the section in place.

The gluing was messy till I got the hang of it. It cleans up well so no problems.

Its worked out well. Trick that you old hands know is to fix the base first. Next step is a bigger one on end of shed..