ABXY build a mold (or use the one I built)

Print 1x of the bottom, and 2 of the walls, and get to making your very own silicone mold. 

for the first part of the mold, attach 1x wall piece to 1x bottom piece, and secure it with hot glue on the outside. place the buttons on the shapes and pour silicone. After the silicone has cured, removed the bottom, while leaving the wall and silicone together. clean the mold, and place a second wall piece on the bottom of the first, then pour silicone for second piece of the mold.