Looks good.
Did you seal the seams?
Only things I do different are moving vent holes closer to the top or place them on the top an use a router. If you don't have a router ask around an if your lucky one of your friends will. Butt joints work but routed edge ones work better. The setup time is longer then the cutting time. That's the bad part.
What are the prices for 4x8 sheets in your area? I've been waiting for five months for an order.
Thanks for sharing!