This is the freely available version of the TK21 Coldcard Case that can be purchased from [CryptoCloaks](http://https://www.cryptocloaks.com/product/tk21-coldcard-case/).
Check out the [CryptoCloaks File Factory](https://www.cryptocloaks.com/file-factory/) for the STL to print your own or head on over to the [GitHub repo](https://github.com/TiKawamoto/3d-printing/tree/master/TK21%20Open%20Coldcard%20Case) for more details.