I bought the router bit off Amazon. $23 (https://www.amazon.com/16-Depth-Slotting-Cutter-Set/dp/B0002TUCRA/ref=sr_1_1?ie=UTF8&qid=1471212918&sr=8-1&keywords=router+bit+for+t-molding). It worked great. Just make sure you do it BEFORE you put things together and any screws are added. I learned from my mistake, and it was an obvious one, but those screws can really eat that bit! :) Stupid mistake, and I know it's obvious, but when you're anxious and wanting to finish your project it is easy to overlook! :)
I minored in Japanese! And forgot all of it...
BUT, it looks like a router bit for cutting t-molding. I have one that I used to build a vidoe game arcade. Here's one on Amazon,
http://smile.amazon.com/16-Depth-Slotting-Cutter-Set/dp/B0002TUCRA?sa-no-redirect=1