Need design advice for interlocking parts

[akirson]

New to the board and to 3D printing, and looking for advice on finalizing the design, and choosing the material and printing technology. I have designed a pair of interlocking plugs in Sketchup to lock the ends of two boards at 90 degrees. See photo - shows two separate plugs, but I changed the design to make the two into a single plug, as shown in the Sketchup model. The two boards are extrusions made from Resysta, a manufactured material used for, amongst other things, siding on a building. The two interlocking parts "plug" into the ends of the extruded boards and lock them together. See second photo. I need 20 sets of these plugs. The installation is outdoors in Chicago. I can create .stl files from Sketchup and upload to a 3D printing site, but I'm not sure if I need to allow space around the "tenons" for clearance? Will the parts that fit into the other parts need to be a smidgen smaller? I do want a "friction-fit" not a loose fit.I thought of specifying TPU for flexibility, but the colors are very limited - the boards are brown, so I want the plugs to be a similar color. Would a different material be better?Any advice would be appreciated. Happy to share the Sketchup file, too if that would help.Cheers,Allan