The side panels are usually milled from HDPE with a thickness of 6.35mm (6mm works as well and might be easier to source in some countries)

Other materials have been used:-

• Melamine MDF
• Hardboard
• Acrylic there are concerns it might crack around the bolts for mounting, washers may be advisable)
• Masonite Pegboard
• Plywood (hardwood such as birch is preferable. Plywood is deforms easily around bolts, washers and upgrading the “M3 x 10mm Hex head Bolts” to “M3 x 12mm Hex head Bolts” may be advisable)
• Aluminum

Other possible solutions:-

• Delrin
• Dibond
• Almost anything that’s 6mm thick and not stretchy should work.

The Railcore II font seen on side panels is Windows 10 “Middle Ages”