Sooo This isn't based off the Actual model, just the sign he has posted at the end of the model.

Update: I just printed it, aaaaaaand it's not bad, it's not square but it does come out well. If you guys want I can post the Top part and the bottom so you can do Dual Extrusion

Update 2: Posted the two parts. I did this quickly so it's not ridiculously clean around the edges, I'll come back and fix it later