Space10 in cooperation with Ikea Lab releases open source how to manual to build spherical growroom for urban gardens. Using their plans you can cut precise plywood parts and use this howto to assemble this DIY Growroom.
Would work well for herbs, cannabis grows to tall I think 
https://medium.com/space10-the-farm/space10-open-sources-the-growroom-aa7ca6621715#.i02x4tt5a
