I am a long-time (part time) fine art photographer -- photographing and working in the darkroom for more than 40 years -- but I have turned to printmaking in the last year.
I have never had a lot of money, so I have built almost all my own equipment -- including my own cameras and darkroom equipment.
I could not even begin to afford purchase of an etching press, so I decided to build one from scratch. I have developed reasonable machining skills from having built the cameras, etc., so I designed and built the thing from complete scratch (with my own two hands - no outside labor or services involved) from "scrap" raw materials which I collected slowly over a half a year.
The bed of the finished press is 24" wide, and it is 34" long overall. It is made (mostly) of 3/4" aircraft aluminum (6061), though some parts are heavier.
The platen is fully supported by steel rods and plastic bearings for the full length of the bed.
I made the rollers using a somewhat unique design, at least for what I observed in my study of existing designs. They are a composite assembly of steel and aluminum. They were considerably more difficult to make than solid rollers, or hollow rollers with welded ends, would have been. But I did do some analysis of what I thought the stress loads problems would be; I believe the finished rollers are stronger than equivalent-sized solid steel, but weigh about 1/3 as much.
The upper roller is 3.5" diameter; the lower is 2.9" diameter. I turned them on my lathe so they are concentric and smooth within 0.001" over their entire size.
Weight (or lack of same) does seem to be the biggest problem with the press -- it only weighs about 150-ish lbs. I made a "crank" drive instead of a "wheel", so there is a fair amount of "vertical" force in the direction of lifting the press for 1/2 the turn. I need to make brackets to bolt the press down to the cart I made.
The press has a 1::2.8 chain drive made from ANSI #40 chain and solid steel sprockets. That has a breaking strength over 8000 lbs -- strong enough for sure!
The upper roller "tensioners" are driven by 1/2-20 steel threaded rods. Then,even with relatively crude paper scales to gauge the top roller's height, the actual height of the top roller can be easily determined within about 0.005", because the screws lift or lower the roller 0.050" in one complete turn. Hence, no micrometers are needed to achieve ablout 0.005" repeatability.
I have also made a UV light box suiltable for up to 16x20 prints, though I only have a 14"x17" (home made, naturally) printing frame.
I have also been doing a lot of research into digital negatives (well, digital positives), starting with the techniques in Mark Nelson's "Precision Digital Negatives".