Neat idea! It's simple but very effective - and I really enjoy the detail of the benches and the tree. Very nice.
I wouldn't add it to any of my sites due to the unmoderated nature of it - seeing some fairly unsavory things in your demo - but that's just a little tweak, I'm sure!
The answer to this question is important to understand, otherwise this marketplace may seem attractive to lesser-scrupulous companies and scoundrels, and keep the legitimate players away.
Likely to avoid defeat attempts. The corporate email requirement acts as a first-line defense to at least try to stave-off would be skimmers / scammers grabbing the CAD file and working out the measurements needed to defeat it.
I wouldn't add it to any of my sites due to the unmoderated nature of it - seeing some fairly unsavory things in your demo - but that's just a little tweak, I'm sure!