PinePhone to Samsung Galaxy S20 Ultra adapter

3D-printed back cover for PinePhone that fits Samsung Galaxy S20 Ultra accessories, such as battery cases.
Model on Thingiverse

Inspiration

PinePhone, being a niche product, does not have a wide variety of aftermarket accessories, specifically, battery cases. However, Samsung Galaxy S20 Ultra smartphone matches PinePhone's dimensions and button layout very closely. This project was inspired by a thread on Pine64.
Unofficial PinePhone Battery Case thread on Pine64 forums

Creation

I purchased a Galaxy S20 Ultra battery case, and the PinePhone fits the case's width perfectly, but there were some issues:

• A gap on top, which I expected.
• A thin gap between the PinePhone's back and the case, which makes the PinePhone loose and puts stress on the USB plug.
• And, most importantly, the power button on the case is not aligned with the power button on the PinePhone, and the case constantly presses on it.

There is a great PinePhone back cover made by Remotheman on Thingiverse. It's simple (no complex curves or shapes), easy to print (i.e. no large overhangs), and fits the PinePhone perfectly.
Remotheman's PinePhone Back Cover on Thingiverse
Despite the license listed, the description allows remixing his design, and I kept the watermark.
My back cover has added length, beveled extension to fit into the top of the S20U case, and beveled bottom to account for the rounded shape of S20U and the case. The buttons are printed with the cover, are narrower, and have protruding shapes offset to match S20U buttons (specifically, the power button).