flat bar couplers
thingiverse
I'm a penny-pincher through and through. Aluminum flat bar can be had for anywhere from 50% cheaper to 10 times less expensive per foot, depending on what brand you choose. This nifty coupler makes it easy to connect flat bar pieces with just a snug fit. The STL file is specifically designed for 1/8 x 1 inch flat bar, but the SCAD file lets you customize it to suit your needs.
Download Model from thingiverse
With this file you will be able to print flat bar couplers with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on flat bar couplers.