Other than modern PCs, what other products are intentionally transparent, so that you can see the machinery inside, for aesthetic reasons?

The glass frog.

All electric appliances in American prisons.
As can be seen here.

Certain lingerie.

The Gameboy has a transparent version.

Wristwatches

Astrolabium Brass Clock I, https://www.scullyandscully.com/home-decor/clocks/mantel-desk-clocks/astrolabium-brass-clock-i-mahogany-finish.axd?gclid=CjwKCAiAgvKQBhBbEiwAaPQw3NfiTsxFUw3GUEsn9sCK9o23EMe9OEsNwaAMdSBwhBwSEeUhgS7mFBoCINMQAvD_BwE

Roberto Robot.

I have a transparent calculator someplace.

The coin sorting toy I had as a kid.

Some elevators.

The Pompidou Center in Paris “was the first major example of an ‘inside-out’ building with its structural system, mechanical systems, and circulation exposed on the exterior of the building. – Wikipedia.

Speculums.

Harris Catch and Release Mouse Traps

https://www.walmart.ca/en/ip/Clear-Bags-Stadium-Approved-See-Through-Tote-Bag-Shoulder-Strap-Large-Transparent-Bag/PRD3K6VCBMTKTNB

Transparent sdadium totes for security reasons.
Clear garbage bags for saftey reasons.

I once used a key duplicating device in a store. The top was transparent, allowing you to see the new key being made.

Speculum are not clear @Kropotkin! They’re metal and cold.

https://nerf.hasbro.com/en-us/product/nerf-modulus-ghost-ops-shadow-ics-6:43ED7D6A-B877-4D61-AA53-3820251AB142

@Dutchess_III Some PCs don’t have windows either.

What?