I am very concerned about falling, I did something similar to Zilla, however, I used some heat hardened bamboo out of my yard. Light, natural, cheap and sturdy and no chemicals were used to grow it.
Oops, I just re-read Zilla's post. I put the bamboo support inside the spreader bars. Same principal I think, added strength with a small weight penalty.
I recently finished a DIY Bridge, I just used bamboo for the spreader bars, so far so good.
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