Halloween Sentry

I've wanted for the longest time to have a halloween-themed sentry for engineer, who always seems to get the raw deal with themed items. It also saddens me that there are literally no other sentry alternatives aside from the mini.

So I started making one. Unfortunately I have no idea how to get it from model, to in-game reskinning of the stock sentry so that will involve a lot of screaming at my PC as I mostly trial-and-error my way through that hurdle. This is why I've started this so early too. If anyone can offer any help or advice to that end it would be fantastic though.

Anyway, the actual sentry. I've kept it in the same form as the stock sentry so I can re-use the skeleton and animation, and at the moment I'm trying to emulate the TF2 painting style.