Here is the way to build diy gymnastics bar at home without any experience:
Cut legs, Build legs, Cut feet and Find Crossbars:
Cut the legs, which have to come down from a roof and then go over into a car. All four legs have to come down together, so you have to take a ladder, make a head hold and then cut the legs with a jigsaw. Cut your legs down, with some kind of a blunt knife, and then use a nailgun to nail down each leg to the bar. Use a workbench to nail the bars to the legs. The idea is to have the bars supported over the cars so that they’re not damaged when used. You also need to make some feet and find crossbars to support them. Make the feet by drilling holes in the ground and fill them with concrete. After this step, you need to buy the safety bars which cost around USD$30 each. You’ll have to glue them together. Choose the best glues so that they hold well and last for a long time.
Leg Braces, Drill Holes, Attach Feet and Attach Leg Braces:
Place the legs braces across the two pillars. The bar can be folded in either direction but the leg braces will keep the bar straight and stable. Place the alligator skin drill holes along the bars and attach them to the pillars. With the hooks up, then attach the leather straps and the false footplates to the bar. Make sure that the bar is comfortable. Adjust the legs braces and the bar to give you firm support. Try the drills and make sure that the bar is free from any flexion. How to Build a Gymnastics Bar (Non-Metal Bars) If you can get a gym or a workshop, than you could try your hands on making a gymnastics bar.
Attach Bar and Attach Crossbars, Construction :
A gymnastics bar is of such great importance that before you start to construct it you must attach a temporary bar to a sturdy surface or stable beam. A gymnastics bar is a metal bar that has a square cross section. This means that the bar has to be extremely sturdy. The kind of width and length of the square cross section depends upon the kind of movement that you want your gymnast to learn. The easiest way to attach the bars together is to use a welded angle joint. The bars are welded along their centre line at an angle that creates a gap of at least 180 degrees between them. However, they are so strong that they can actually support more than the required weight of the bar. The uneven edges of the bars are also sharp so that they don't cut the hand of the gymnast.
Warning and Conclusion
Do not have any health issues. Follow safe gymnastics bars making at home with proper methods. Any mistakes from experimenting with gymnastics bars at home will cost you huge money and injuries.

