Need ideas for window vent

[rrob311]

I have an extension kit for my monitor heater and I need to vent it outside a window above. Drilling a hole in the wall is not an option as it is not my building. Does anyone have any ideas on a material to use to cover the window with and drill a hole in? I was thinking maybe plywood but if there is a composite or insulated material that works better please let me know. I need to get this unit setup asap.

[OnTheEdge]

Monitor Made a "Window Installation Kit P/N 8208, 8209 kinda works like installing a window AC in a double hung window. Not sure if it would work in an awing or casement window.

[rrob311]

I have the window kit in my house. It works ok but the seals are old. I ended up cutting a piece of plywood and taking out the window at the business where I need heat. So far so good but I will have to weatherproof the outside of it as it is a very damp area.