I found some website which have pictures of some custom built props made for various TV-series.
They had listed one MacGyver prop called ERMA device, which was from episode Deep Cover. Here's the caption:
"Originally built by SFX department of the TV series MacGYVER as a "Submarine Cloaking Device". It was subsequently obtained by MMPP INC. and repeatedly modified for various other production purposes"
https://www.productionhub.com/galleries/details/3735
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