Genius or Madness? Homebake Engel on Gumtree

I spotted this listing today, asking $400:

Gumtree said:

Engel fridge 50lt esky
50 lt esky able to store ice for 6 days by itself now fitted with an Engel refrigeration unit. This unit has all the benefits and reliability of an Engel with superior insulation properties over a standard fridge. The wall thickness including the lid is twice that of a standard Engel. The end result is the refrigeration unit barely has to do any work and has a lower power consumption than a standard fridge. Comes with standard Engel power leads. 240v and 12v with an Anderson style plug fitted. Robust esky body does not require a bag to help with cooling like a Waeco.

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I've never seen inside the guts of any the newer long last style espied.
Yet I do have 3 large, and one smaller.
Are they styrene filled?
A trick for the old type was to drill a small hole up under the lid in one corner, 6mm, and in the opposite corner is drill a hole just big enough to get the filler tube in from expander foam/ space invader.
Pump it in until the small bleeder hole starts to have a consistent worm of foam come out.
Tip...
Don't touch the excess at all! Keep it elevated and just wait till it hardens and cut off.

Heat on the air lids killed their performance, and fat mates sitting on the lids would crush them.
Do this with all lids in one hit, as once you crack the foam can, they usually can't be reused after.
Tempted to do the same with my newer style eskies.

Genius!

Fridgemate have been doing it for years, a compressor hanging off the side of a tried and proven ice box.