I see a Cardboard Box and some Duct Tape in your future.

That or a piece of rigid foam insulation and a knife.

A can of spray paint would make it look good and the plywood would give something solid to attach the netting top and bottom to. Make it wide enough that the hole doesn’t compromise the strength and rigidity. Drill the hole for a snug fit of the duct tube.

I'll have a look and report back.

First I have to find a portable a/c that won't eat me out of house and home in terms of energy usage.

We have those. And a Jewson in Tiny Town itself.

#RigidFoamAmMe

I have absolutely loads of the stuff, one never knows when it might come in handy etc

Reasonably well equipped on the knife front too

I have a Stanley knife.

And a load of antique khukuris, somehow

Stanley isn't allowed to have a knife. His thumbs are too tiny.

I'm ok for Stanley knives thanks, but if you're looking to trade, how many cubic metres of rigid foam might cover one khukuri?

It doesn't have to be antique though, I have a pigeon in my sights.

Another approach is to buy a screen for the window type and model which will cover entire window unit. Then pinch the duct pipe with the window opening staying behind the external screen.

He's more built for crushing than slicing, anyway.

If you are olanning to actually use the khukuri, you have to develop a blood-curdling scream first. It's required.



Not sure I'm getting where all the pieces go. To complicate things further, the building is a converted maltings and the windows are completely non-standard and not even the same as each other

It sounds like you are thinking the window opens inwards, maybe?

Amazon UK have anything similar?

Amazon.com: HOOMEE 400CM (157") Universal Window Seal for Portable Air Conditioner and Tumble Dryer – Works with Mobile Air-Conditioning, Easy to Install - Air Exchange Guards with Zip and Adhesive Fastener : Home & Kitchen

In the US many hardware stores or window supply companies can make a custom screen fairly cheaply. This will cover entire window externally. It can be held in place by several options.

Interesting! Their windows seem to open inwards but something along those lines

I'll have a look. The windows open outward though.