Just introducing myself, in order to achieve “not a bot” status, and advance from lurker to actual community member.
I’ve been a huge GB fan since childhood - had a lunchbox, the nerf pack, a jumpsuit, action figures, and anything with a picture of Slimer on it. I like to think that as an adult I have a more sophisticated appreciation for GB now, but here I am wanting to build a pack etc etc, so maybe nothing’s changed.
Nope, nothing’s changed you just have more $$ now! haha… glad to have you here weenog
Hi weenog, welcome to the site dude, lots to read and some great pics for reference, 
Welcome to the site! Make sure to spend lots of time researching before you start buying parts if you build a pack. There is a lot of information here so it can be overwhelming but you’ll be happier if you know exactly what you want (quality of parts/accuracy) before buying parts. I wish I had done a little more research before buying some of my parts, but you live and you learn.
What mistakes did u make James, I’m just about to start my build this weekend!
I am not going to list everything out, but just make sure you plan before you spend. There haven’t been too many “I wish I wouldn’t have done that” moments, but I’ve come very close to some. Usually when someone comes out with a new item for sale and I think “I have to have that!”. For instance, if you are buying a shell and motherboard make sure the motherboard fits the shell. Or make sure you don’t go buy a motherboard only to find out the shell you finally decide on 3 months later will come with one.
My advice would be:
1.) Pick what kind of pack you are planning to make. GB1? GB2? RGB? Hero? Stunt? Semi-Hero?
2.) Research that pack. There are differences, do you know them all?
3.) Pick how accurate of pack you want to make. If you want to have a very accurate pack you will spend a lot of money or a lot of time. If you make a pack out of wood, with mdf motherboard, and random parts from a hardware store you may be very happy with it and it may look pretty close, but it won’t be considered a 90+% accurate pack. For that you will need both the right dimensions, the right materials, etc.
4.) Research what plans you will use as a guideline. Make sure you understand what is incorrect on the plans and if you want to fix them to make them more accurate. Some don’t include all the details. Are you going to have a rotating barrel with extending tip?
5.) Research the parts, where they go, what was originally used.
6.) Make a complete parts list of everything you want to buy. There are a few lists floating around but they aren’t necessarily complete or include the fine details. Include what kind of material you want, or if it will be real or replica. For example you can buy real clippards or resin copies. Depending on which you go with will decide the price and accuracy. Did you include all the right bolts you will need?
7.) Start looking in the for sale section for who sells the parts you are looking for. Then look at the feedback section to see if they have a good track record. If you want close to 100% hero accuracy you will need aluminum parts, which will mean a very long wait from current sellers, unless you can build them yourself.
8.) Research the prices of the parts and the wait times. Can you afford the price tag of the parts at the level of accuracy you want? Are you patient enough to wait that 7 months for that very accurate part?
9.) Once you have decided on what parts you want and can afford, then start purchasing. Don’t go buy a bunch of resin parts, realize they were really aluminum on the screen used packs, and now decide you need aluminum.
10.) Research older builds. What did they use? How did they assemble?
11.) Build and have fun!
It’s really what you make it. And only you have to be happy with it in the end. But the more you research, plan, research, plan, research, execute the easier it will be and happier you will be when it’s finished. Did I mention research? Finally when you have questions or don’t know how to do something use the search feature. Any question you have has probably been answered several times. It can be hard to find the answer occasionally but don’t expect people to be nice or answer your question if you haven’t attempted to search for it yourself. People are very happy to help out as long as you do some leg work first.
Just brilliant, thanks for the cool heads up! It’s give me a lot to think about, I think I’m going for semi hero, as many original parts as I can!