well, if you were doing design for, say, injection molded parts, there are sources with detailed guidance on most of the materials you could be making your part out of-
but in truth- you learn mostly thru practical experience.
This is especially so for a novel technology like SLA- where the variables are so great.
Car parts that are stamped or vacuum formed, - for example- are mostly designed to accommodate a fairly wide latitude because there is a lot of potential variation from one part to another so you often parts with wide overlaps, or with slots instead of round screw holes- or with mounts, like car door hinges, that can be adjusted to optimize fit with surrounding body panels- injection molded parts that at small can have very tight tolerance- but as they get larger, so do the potential variations due to warpage.
Being a designer is essentially an exercise in understanding the limitations of production technologies, and designing something that can be made using that technology.
Another example is Wrenches- these are match plate, rammed sand foundry cast in steel… but there is no way to get a precise tolerance on the business ends of the wrench in a foundry process- which is why you can see the sandy texture where the sand casting was adequate for the handle- but the actual working ends are clearly machined.
if you look up the white papers that formlabs had put out about fitment and tolerances for such things as snap fits and such- they can give you a good starting point of understanding how much slop you need to design in to get parts that a functionally good enough. Rough ideas of how much larger a hole has to be than a pin in order to fit freely- closely, or tightly … that kind of thing.
as to whether designers keep different versions of one design- I dunno- I never do-
As A designer, I consider what I am making, for what purpose and out of what materials- and from there I select the method or methods of manufacture that best suits the objective of the design…
It might be a mix of parts- some of which are off the shelf- others parts may need to be injection molded, and still others stamped in sheet metal…
And once I have a plan for production, I do the modeling work for each part based upon those design decisions.
while I might 3D print a part as a prototype of a part I intend to injection mold… I am not interested in a version designed for 3D printing- I want the prototype to represent the injection molded part, for evaluating how well it is designed for injection molding.
I know a 3D print will not be identical to the final injection molded part- but that does not matter, its still close enough to be useful as a prototype.
If I am designing something for 3D printing as final means of production, then I will try my best to design around the issues of 3D printers- but I am also designing to play to the strengths that 3D printing offers- like I can print shapes I cold Never injection mold.