One of my favorite parts of building things is playing around with different materials. The original catalyst was built using angle iron. It was strong and could be put together relatively quickly. It was totally over-engineered, but it worked.
This catalyst is printed on a Thing-O-Matic 3D printer. Yep. its the future. We are still experimenting with the type of plastic and infill, but hopefully a working model will be online shortly.
This particular print was done with ABS plastic and 30% infill. It held my weight when I carefully sat on it, but collapsed when I lifted my feet. We are currently printing one with 100% infill.
You can download the STL 3D file at Thingiverse.