Puffy pentagon

This construction is made out of five copies of That Simple Unit (TSU),That Simple Unit (TSU). Origami by Michał Kosmulski. Michał Kosmulski (2006-07-05). attributed to Charles Esseltine.

I found this a little tricky to fold and put together, but the end result was very structurally sound.

The fully assembled pentagonal bipyramid.