Crypto - A puzzle Joust

It turns out I am not the only mad scientist woodworking type out here in the vast expanse of 8 billion people.
 
A good puzzle friend and college Robert Yarger has been at this far longer than me, and one day he invited me to a puzzle joust. 
In this puzzle maker's joust, the idea is that I would build a puzzle box and ship it to him, for him to then build another puzzle around the existing mechanics.  Robert would then, ship it to me for me to repeat the process again, locking his previous work.  One last time I ship it to Robert for him to make one last effort to block my mechanisms once again. 

In these jousts we build two, one for him and one for me.  No money is exchanged between us, and we are free to do what we want with our copies.  One of the copies we donated to the Lily Puzzle Library in the US. The remaining copy we auctioned off on puzzleparadise.net, and split the proceeds between us.

I think the most challenging part of this build was not just making a puzzle mechanism, but artistically creating something that looked balanced, like a finished piece, like as if one of us made it all the way right from the beginning.  

What made me happiest was challenging my own abilities and belief of what I could and couldn't do.  

This has been such a fun and exciting project that other puzzle designers / builders have been getting in on the collaborative fun too!

Thanks for looking guys!