Need help making window inserts

So I want to make some window inserts. Saw some from a company called Indow Windows but way too much money, like they should be 1/4 of the price. Problem I'm having is that I live in an apartment so I need something I can slide in and out of the window in the same kind of fashion the Indow Window inserts do.

Basically a piece of plexi with a silicone compression tubing around it. Tried looking up all kind of tubing and gaskets but have yet to come across anything close. Figured maybe someone else is good at thinking outside the box on what I could use to maintain an airtight seal.

Also if anyone is knowledgable about all the various option with plexi/acrylic, what would you suggest getting? I want it to be at least 1/4 inch thick (if not possibly go with thicker) and if there is anything that will not yellow over time as I know plexi has a habit of doing that.

 

Nobody around or just nobody has any ideas?

 

Have you looked at adhesive backed weather stripping? If wrapped around the edge of insert, will seal on 2 of 3 sides of the perimeter.

 

This might be what you're looking for:https://foamtapes.net/weatherstrippi...ionbundle.aspx