This is a model of a bead board with a design based on one that is for sale at Michaels. The dimensions should be nearly identical and perform nearly the same as well.

This bead bracelet tray can make bracelets in 7 ¾, 7 ½, 7, 6 ½, and 6 inch sizes. (That is 19.7, 19, 17.8, 16.5, and 15.2 cm for metric users.)

The top and bottom have room to mark out inch and centimeter rulings, as well as the tray has 2 extra min trays to store extra beads.

The overall dimensions are 12 in x 9.4 in. (30.48 cm x 23.876 cm)

I have included extra files that split into 4 pieces for smaller printers, as well as including my Solidworks model for anyone who would like to edit it in any way.