Looks like 2x4s and steel brackets.

I 3d printed custom brackets, attached the dome to 2 trampoline frames, and used a compound miter saw to custom fit the skeleton together.

The blog post goes into more details and provides resources to lookup even more info on the materials and processes I used, ranging from custom designed 3d printed ASA brackets, to Japanese style woodburned treatment finished out with 3 coats of shellac, and a variation of latex cement canvas stapled like upholstery out of used painters drop cloth and free up cycled paint from the Austin recycling center.