BENECREAT 5 Sheets 3mm White Foam Boards 11.8x7.8inch Rectangle Foam PVC Sheet Poster Board Mount Board for Mounting, Crafts, Modelling, Art, Display, School Projects

the standing units also require modifications to the window if you don't want to leak a lot of heat back in. The make adapters out of cloth and wire. One time (apartment in the USA) I went down and had a sheet of plastic/acrylic cut to fit my apartment window with a correct size "hole" in it for the "tube" that expels hot air from the portable AC unit. I used regular Scotch packing tape to tape it in place. Total cost was maybe $45 all in. But going all the way down to basics: buy foam poster board for $9: https://www.amazon.com/BENECREAT-Rectangle-Mounting-Modelling-Projects/dp/B08M3FYVYW/ which is water proof, cut it with any scissors you have (or borrow scissors from a neighbor for one hour), and tape that mess together with any tape you can find. Clear scotch packing tape works, so does regular tape of any type, but here is the scotch tape: https://www.amazon.com/Scotch-Shipping-Packaging-Dispenser-142-6/dp/B000J07BRQ/ is not just a simple thing I claim it is. I claim in less than 1 hour of fiddling around a 14 year old can do it. It is an attitude thing: I don't care how ugly your first try is, a few apartments later you'll be designing insulated 3" gapped foam boards filled with expanding spray foam between them: https://www.amazon.com/Great-Stuff-99108860-Dispenser-Sealants/dp/B07JDJ28LW/ and using $6 brick pattern wall paper so your landlord doesn't notice from the outside: https://www.amazon.com/Hopeak-Self-Adhesive-Waterproof-Decoration-Renovation/dp/B0B6FNPMDT/ LOL. I think people are just afraid to try a little redneck engineering nowadays.