Here is a way that anyone can inexpensively make a set up to do Arch Ups and HLLs.
The first video shows my set up, with eye hooks bolted to a wall and a pelvic swing.
The second video shows how this can be done very inexpensively with some slack line and a strong door.
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Please note if you do make the straps, have a good 10 cm of overlap and lots of extra stitching, its you're forehead that will hit the ground if the sewing is weak.