The author remixed this model.
The design is a bit thicker and I added holes for magnets on the back. I used these : https://www.amazon.com/Magnets-Refrigerator-Cylinder-Whiteboard-Miniature/dp/B0936M3WPK?pd_rd_w=qKRYi&content-id=amzn1.sym.7d8251a9-42fe-402a-a341-0f37d967c460&pf_rd_p=7d8251a9-42fe-402a-a341-0f37d967c460&pf_rd_r=7ES2QS35PZER5FTZK97F&pd_rd_wg=2yZdm&pd_rd_r=f449a903-76fa-4696-b142-d18c48ca43ac&pd_rd_i=B0936M3WPK&ref_=pd_bap_d_grid_rp_0_1_ec_pd_nav_hcs_rp_1_t&th=1
Uses 4 magnets and just superglue them in place.