[I await your comments!] -- OK!!! I'll throw in a few of my personal comments on this topic for everyone to read.....
WA-A-A-A-A-A-YYYY before I actually became a "PCB Designer", I was a "Private" in the military stationed at a -- literally -- SECRET base located in the middle of the Utah desert!!! There wasn't - ANYTHING - around this base for 100-miles in every direction but flat desert and Salt Lake City was just over 90-minutes away, while driving at stupid high-speeds on unpopulated desert roads!!! OH, YEAH!!! To be young and foolish during your early 20's!!!
This military base is where the U.S. Army conducted a lot of their CBRN (Chemical/Biological/Radiological/Neurological) tests and some of these test sites are/were several square miles in size. So.....imagine a radio-type broadcasting tower being several hundred feet high as a "center-point" and then try to imagine thousands of "receiving test stations" located in dozens of spaced concentric circles or rings, with each "test station" located maybe 25-feet or so from one another. Since each concentric ring of "test stations" becomes ever larger and larger and with the furthest ring being a mile or two away from the "center-point", you can only imagine how many "test stations" there had to be overall. It was all staggering to me!!!
These "test stations" all fed their data back to the "test-site central command" building that contained, at the time, an IBM main-frame computer. The IBM computer would receive all of this data, analyze it, compile it and record it on those fast-spinning tape decks that you now see in "SCI-FI" movies. So.....what does all of this have to do with "home-etching PCB's" you ask??? Well.....this:
The engineers who were involved with these tests complained about the incoming data becoming corrupted and ruining their test results. "What can be done to fix this?", they asked. The "Head Director" of this testing group asked an Electrical Engineer who was from Michigan if he could design any circuitry that could clean-up the data signals as they were coming into the IBM computer. The Electrical Engineer guy said, "Yeah.....Sure"!!! Then.....the "Head Director" looked at -- ME -- and said, "Well, Williams.....his circuitry is going to need to be put onto some Printed Circuit Boards -- AN-N-N-ND -- the circuit boards will need to be put into some kind of an enclosure. So.....why don't you just figure out on how all of that needs to be done, OK"??? WOW!!!
So.....here it is in the year of 1972, I had hardly even seen a Printed Circuit Board at that point in my life at that point in time and the only "kind of" mechanical design I had ever done was during my "Drafting" class when I had "Shop Class" in the 9th-grade!!! OK.....This will certainly be interesting!!!
So.....one day the Electrical Engineer (Dave) and I get into a military Jeep and drive-off into the desert to visit several of the actual "test stations" so he can make a series of electrical measurements of them in order for him to know what type of data they are outputting and all of their parameters. As mentioned earlier, since these test sites were each several square miles in size, it took us several hours to not only drive from site-to-site, but also to drive around each test site to a number of the test stations. And, being out there in the middle of the Utah desert, under the direct desert sun, it was a rather hot, dirty and sweaty job!!!
After Dave had collected all of the electrical information he had needed, we drove back to the "Central Command" base and Dave set about to analyze his measurements against the schematics of the "test stations" and began to design circuitry that would "clean-up" the data being fed into the IBM computers. All of this was just "the first step" of the process.
While Dave was designing his circuitry, I was quickly forcing myself to learn about what it would take to "manually hand-tape" Printed Circuit Boards, since I had -- NEVER -- done this before!!! From somewhere, I got some kind of a catalog that had the materials needed to "hand-tape" PCB's and I ordered a bunch of it. In addition, I also had ordered some large rectangular glass baking bowls for cakes, some etching solution, photosensitive PCB laminates and other materials. In addition, I also cleaned out some sections of a large "locker" assembly (like used in a gym to store your clothing and personal items) and created a small and cramped "dark-room" with a swivel-lamp to expose the artwork onto the laminate material. You really had to be "creative" back then when things didn't exist or could be just bought like you can today!!!
After a couple of weeks, Dave finished his circuitry design and he had come up with 8-circuits that he felt would clean-up the incoming data from the desert "test stations". Now, it was up to me to convert his schematics into 8 different PCB-designs, which was something I had -- NEVER -- done before!!! This'll be good!!!
Because I was generating all of the PCB layouts "manually" with no photo equipment, my layouts had to be done on a 1:1 basis of the actual size. And, since this was 1972 and being located in the middle of the Utah desert, pre-set footprints like those that were available from "Bishop Graphics" during the later 1970's just weren't available to me then and I had to manually create all of the component pin-spacings and pad sizes, in addition to coming up with a workable components placement and routable PCB.
But.....I persevered and managed to layout all 8 of the circuit boards. Dave and I kludged together an etching station which also included a small motor assembly that rocked the glass enclosure back and forth to help the etching solution do its thing. When all of the boards had been etched, just like what someone else here in this thread had mentioned, I had to sit down in front of a drill press and manually drill-out all of the component pads so I could mount and solder all of the parts. There were a whole lot of holes to drill out!!!
Since there were no silkscreens on the boards, I had made some kind of an "Assembly Drawing" of each board so I knew where each part went and their orientation. Amazingly, all of the boards and their parts soldered very easily and the finished boards looked really great when each one was completed.
Mechanically, I had designed a small card-cage enclosure for all of the circuit boards. However, for some unknown reason, my memory of the mechanical design details about this project just "aren't there", so I will have to skip that part here.
However, I do remember that the finished mechanical card-cage enclosure and its 8 circuit boards were all designed to fit within a small empty hole within a mound of electronic equipment were contained within a large radome that was mounted onto a flat-bed semi-trailer truck outside of the building which housed the IBM main-frame computer. I had to crawl inside the radome and then crawl into and then behind all of the equipment in order for me to wire-up my little enclosure to the IBM computer wires. It was really weird for me doing all of this as I "knew what I was doing, but I didn't know what was really going on"!!!
A few days after I had installed my little enclosure into the radome equipment and the Electrical Engineers who conduct the tests there at this military base had determined that electrically everything seemed to be a "GO", they then conducted some "Mustard Gas" test out at one of the test sites and all of the engineers very eagerly closely watched all of the data streaming into the IBM computer. Tensions were high in that computer room for the first few minutes!!! Then..........they all looked around at each other and everyone started hooping and hollering and screaming and yelling in JOY because.....for the first time, > ALL < of the data coming into the IBM computer was "clean as a whistle" and was perfectly recorded onto those fast-spinning computer tapes!!!
With me being only 23-years old at the time, I stood there within that computer room and I was amazed to realize that my efforts of not only coming up with the mechanical design of a small card-cage enclosure, but also the PCB-designs of several small circuit boards of circuitry that did "something" to this electrical data coming into the IBM computer made all of this important stuff actually work!!! This experience showed me that -- I -- can "make a difference" in a bigger picture of things. AMAZING!!!
Fast-forward about 20-years.....and I then find myself sitting in an R&D laboratory at the NASA/Goddard Space Flight Center designing 8- to 16-layer Printed Circuit Boards on a computer using CAD-software that costs $20,000 per seat!!! Some of the PCB's are so complex with thousands upon thousands of nets that it takes an auto-router an entire weekend working 24-hours a day just to route these circuit boards!!! And, to think.....I had designed my first 8 circuit boards with absolutely no previous experience or knowledge of what I was doing other than using my "common sense" on how I thought things should be done.
Now.....I have nearly the same PCB-design software as I had at NASA installed here-at-home on my home computer. Life's good!!!
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I got #34. 
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