This is a case design for the Helix ortholinear split keyboard. There are designs for both 60% and 40% variants. There is also optional tenting and underglow. The top lid fastens to the base via 6mm x 3mm neodymium magnets. The lid is designed for the OLED screen to mounted very low, close to the MCU.
M3 inserts: https://www.amazon.com/dp/B07LBRB5HL?psc=1&ref=ppx_yo2_dt_b_product_details
3mm foam: https://www.amazon.com/Neoprene-Adhesive-Padding-Multi-Function-Soundproof/dp/B08RB2FWVR/?th=1
1mm foam: https://www.amazon.com/gp/product/B07L6KV4QG/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
The author marked this model as their own original creation.