This is a magnet-mountable marker holder, with 12 spaces for 16-17mm chalkboard or art markers. Fits on the “Perch” style steel mounting boards, including the “Wally” and “Mini Wally” mounting plates. I also designed a version without individual marker holes, if you'd rather have just a cup to use for whatever you need. 

3 holes on the rear allow for the addition of 3x 2.5mm x 10mm round magnets.