July 31, 2021 Update: This week I divided my time between working on the root cellar and an expedition to Boulder Lake.  Right now, I'm letting some sealant dry on the root cellar, but early next week I'll be ready for the moment of truth: refill the hole with dirt and see if the structure can withstand it.  Obviously, I think it will, but there's still a bit of suspense as the moment approaches.  Anyway, this weekend I think I'll post the video of a shear strength test I did on some 3D-printed materials a while back.