It seems like the common solution to holster a (usually toy) PKE meter is to buy and modify a holster for a measuring tape. I wanted something that evoked the original belt gizmo and trap holster, so I set out to design and build a custom PKE holster from leather.
Leather, man
After watching some how-to-videos on working with leather I made my way to Tandy Leather out by the Portland Airport. I found a scrap piece that was large enough for my design (though a little thicker than I wanted). Kudos to the manager there who gave me a deal on the piece (around $20 IIRC) and offered helpful advice.
I mocked up my prototype from old cereal boxes, making sure both my 1989 PKE meter and newer, more-accurate PKE could comfortably fit. I used this to guide cutting out the leather. I built a form from plywood, soaked the leather, and clamped it to the form to hold the shape.
I dyed the pieces black and applied Super Sheen. I glued the pieces together with E6000 glue.
As my leather parts were a bit too thick to accommodate both parts of the snaps I ran small screws though the leather and into the hollow shafts of the snaps, secured with glue, to strengthen those attachment points.
I glued some felt to the interior to mitigate the leather scraping my scratch-built PKE meters.
finished
My finished holster nicely complements the leather piece Bryan Ambacher built for our belt gizmos back in 1985. Perhaps some weathering is in order at some point.