Nautilus Shell (Ursula Seashell without cutouts or ring)

**TL;DR**: this is a remix of [Nautilus Shell](https://www.thingiverse.com/thing:9177) by @tc_fea that has been scaled and mirrored to be identical to the [Ursula Seashell](https://www.thingiverse.com/thing:744504) design by @Firepixie, only lacking the cutouts and necklace ring of the latter.

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I recently decided to build a second one of these [Adafruit Ursula's Seashell Necklace](https://learn.adafruit.com/ursulas-seashell-necklace/overview) kits designed by Erin St Blaine (firepixie), but this time I'm building a [tiny battery charger](https://www.adafruit.com/product/1304) (and some extra circuitry for changing to "charging mode" when plugged in) into the design for added convenience. When I made the first one of these about 6 years ago, I realized that charging the battery was really inconvenient, and I didn't like the large cutout in the back of the shell. Hence the need for this remix.

I first set out trying to "repair" @Firepixie's original model to reconstruct the