Simple marker holder for a 3/4 inch (0.75) sized whiteboard markers, example picture uses 1/4 x 7/8x 3/16 magnets (Hillman #54200; 6.4 mm x 2.2 cm) glued into the cavities.
Successfully printed on an ANYCUBIC Photon Mono 4K using EC UV Resin (White SLA) with the recommended settings on the container/anycubic websitehttps://www.anycubic.com/blogs/news/resin-settings-for-anycubic-3d-printers#photonmono4k