Parallel bars are common sight in rehab clinics, used to help those with mobility problems maintain balance as they relearn how to walk. The bars are also a popular strength training tool for fitness enthusiasts and would-be gymnasts. Parallel bars can be costly. The average retail price for a pair is around £1,300. Luckily, making a homemade set for home-based rehabilitation isn't too challenging.
Lay one of the 10 x 10 cm (4 x 4 inch) boards flat on the floor, then lay another parallel to the first. Decide how far apart you want your parallel bars to be spaced: a common spacing is around 60 cm (2 feet) apart to accommodate the different shoulder widths of everyone using the bars. Once your width is decided, lay two more 10 x 10 cm (4 x 4 inch) boards underneath and perpendicular to the parallel planks so that you have a crude square shape that resembles a hash sign ("#").
Use the 15 cm (6 inch) wood screws to screw the planks into place, fastening and securing the parallel planks to the perpendicular wooden base planks. Use as least four screws for each of the four corners. Set one of the 10 x 10 cm (4 x 4 inch) boards upright on one of the corners and use two of the corner braces to attach the board securely. Add two more corner braces to the opposite side of the board.
Continue fastening the three remaining 10 x 10 cm (4 x 4 inch) boards with the corner braces. Lay each of the dowel rods on top of the vertical boards, running parallel with the parallel base, and use the at least three wood screws to attach each end of the rods to the tops of the boards. Check the new parallel bar set for stability and add additional screws/braces where appropriate for additional stability.
Wrap the dowel rods in athletic tape to create a secure grip surface if desired. In lieu of using dowel rods, metal piping can be used. Attach appropriately sized eye-screws to the tops of the 10 x 10 cm (4 x 4 inch) boards and slide the piping through the holes.