It is a learned art, and a significant investment in time, effort and money.
if it was something that could be picked up on a passing whim then everyone and their brother would be making plugs and moulds and the world would be filled with exceptional vehicles of futuristic proportions.
but this is not the case, in order to learn this art, you must "learn this art"
start from the bottom learning glass and fabrication, mould making concepts and requirements, composites fabrication and bonding, CAD design, programming possibly and even then, you need a place to do it in, the ability to have disposable income to finance the errors and mistakes and then multitude of designs and moulds you will make that come out wrong or damaged or that destroyed the master plug as well as the mould from it...
this would not guarantee that all could be applied and create the final objective...
some of us have spent decades learning and are still learning this art by applying it on a daily basis, spending more money than some people earn just to find out that the idea didnt quite work out.
the odds of sitting back and being handed the information without effort put forward would be an insult to those who have gotten their hands dirty and made the investments as well as paying the price.
that being said,
I use several CAD programs, Rhino being a favorite, along with Vcarve and Cut2D Cut3D ViaCad 3d and for final mesh work i use Nettfab Pro.
forms are usually made from plywood as there will be a lot and MDF would weigh a ton... spacing is all about resolution, the closer you slice the design the better the resolution but also the more forms.
foam i have seen anything from pink or blue closed cell to spray foam, either way once in place through hot glue etc. it would be sealed before adding any type of resin.. or guess what you will be doing all over again?...
when you are making the plug all your final finishes will be implemented near the end, this includes the windshield form etc.
making the plug act as the final product is the purpose of the exercise.
once you have roughed it then you will coat it, on foam i use a rosco product which is designed to coat any type of foam once hardened you can almost stand on it... this will be sanded down using normal methods of coarse to fine etc.
once the whole plug is done... several months/years later and after the divorce has been settled and you have found a friend with a garage you can finish the work in, you will clear coat, sand repeat, then wax the plug down several times,and spray with PVA, at which time you will start to make moulds of the individual areas of the plug... a one shot of the whole plug is not going to happen, you have to do it in parts, though you could do the whole car as a final product again huge and hard to handle, so quarters at a time would be my choice.
flanges on everything, dont pull anything off until the whole plug looks like its in body armor and ready to fight in the Jurassic era.
the flanges will be bolted together and matched... the mould will be made in layers over days and weeks, not all at once or you will destroy something with the heat that is going to build up...namely that plug you just put your life into.
so from this and most people will not agree but my next step is to pull those moulds... do a run of each part, create a frame to mount them to that will create the new glass plug, then fit and start to refine the design.
once the new plug has been body worked and all seams and areas are solid straight and acceptable to anyone other than yourself...
you clear coat and do the wax thing all over... and after the PVA you will gel coat the parts with a thin coat which is then backed with filler in the corners and sharp areas and glassed with flanges etc.
once this has once again turned into the punk mutant turtle, let it sit for a week...no peeking.
after this when you pull the moulds you will have a master set of moulds, that you will wax and PVA each and every time you use them without question because thats how you make a prime product, not wax once and pull several times...
there are no shortcuts, there are no easy ways, there are no cheap methods.
anyone who trys to suggest otherwise is not in the thought of a prime result, they are looking for a fast buck and have no concern for the product.
and sure there are about a hundred things i left out, because i am here to help out if some one needs it , not do the work...
so, i am not trying to be condescending by any means... but this is something you need to roll up your sleeves and jump in, no one is going to spoon feed anyone and no person should expect there is a free ride out there, we all got into this hobby to build a car... if you dont want to do that then you are in the wrong hobby...
once you get into a jamb then we are all here to help you out of it... but you have to get into it first...
no prejudice, just my immediate thoughts.