It's a cosmetic set for Demoman. I was planning on making it anyway, but the idea of forcing myself to do it in a 72 hour window was appealing. I chose to do it with this set in particular because of it's deceivingly simple nature.
It actually ended up being considerably more difficult than anticipated, I spent almost the entirety of the third day debugging tedious technical issues (rigging/lods/etc), but that's the nature of making shirt-type cosmetics for TF2. I think it paid off and helped me prove to myself what I can get done if I don't allow myself to get distracted so much.
(I'm going to upload it to the Workshop next week, I don't see much sense in rushing out the promotional art for the jam )