I still have my old Spotmatic, which I bought in the Danang PX in 1966 for $115. I carried a Nikonos most of the time in RVN but it got KIA. The Pentax survived and still takes a great picture.
The internal parts are works of art, excellent machining and finish.
You just can't put them away without removing the battery.
I was worried that the conductive paint would have too much resistance to current but I built up multiple coats. It has good adhesive strength too.
Likewise I bought a Petri when I got stationed at Tachikawa AFB, Japan, in 1963 (can't remember for sure but think it was around $25 or so)and took thousands of pics (actually slides) with it while traveling as a Crew Chief all over Asia as well as my 18 Months in Nam.
Had a built-in light meter and was practically foolproof with regards to taking good pics.
Don't know what happened to it, but over the years it "disappeared."
I still have my Spotmatic II from 1971. However, I took most of my Vietnam snaps with a cheap Kodak Instamatic since I didn’t want to risk the Pentax. Since I flew helicopters this meant those photos were wide-angle with more distance. Still works and at the time only the Nikon SLR was considered better (and cost a whole lot more).
Postscript: as a 54-year old reservist I got deployed in 2003 to Uzbekistan. I had the old Pentax sent to me from home and got some great shots of Central Asia. The young people, both Uzbek and American, were amazed at its heft and durability.