Hackers Help: Alternative or substitute for Expedit/Kallax mirror door inserts

Hello All,

I have a bunch of Expedits (still hanging on to those) that serve as my book shelf, closet, and TV console. I outfitted them with Expedit mirror doors. I want to add another 2×2 Kallax to extend storage but IKEA does not sell mirror inserts anymore.

Can anyone offer any suggestions as to how I can buy or DIY mirror inserts for Kallax? I live in a studio apartment and the mirror inserts add space to the apartment.

Thank you