The purpose of this post is to simply provide those in the niche sneaker-twitter industry the knowledge to go out and do this themselves to produce merchandise for their servers, groups, bots etc. If you're looking to produce one-offs you're in the wrong place and I'll provide details on that further down as it relates to things like MQOs.
Firstly you need to understand how the process works. If you're expecting a drag/drop website or another god awful BTEC way to produce clothing then you're in the wrong place. That's the kind of shit you use when you're vinyl printing hen/stag night clothing or messing around creating a Gildan t-shirt with your mates face on it. Before you even begin to think about anything you need to settle on your design, printing method, type of garment (Sweatshirt, T-Shirt etc) and finally finishing touches, once you've got these down you can move onto actually researching blanks, contacting studios and getting the ball rolling.
Design: Your design must be high quality, ideally original source AI vector or equivalent. If you don't know what a vector is then speak to your designer. If your designer doesn't know what a vector is then stop hiring 12 year olds and find a new designer. Your design must also be suitable for your desired print method, but I'll go into that next.
Print Methods: Most common print methods are Screen Printing, Embroidery, Vinyl Print and Digital Printing.
Screen printing uses screens and ink to apply a design onto a garment, each colour in your design is separated into a different screen and each screen is done one at a time to produce your design. Screen printing often comes with an MQO (Min quantity order) of 25 pieces per design and you're looking at paying £10-20 per screen for set-up costs. Screen printing is regarded as the best in terms of quality and affordability as the more garments you print in a single run the cheaper it'll be per item. There's also numerous different ink types but I'm not going to spoon feed, sorry.
Next up is embroidery, this is charged per stitch count and thread must be colour-matched, your design itself has to be converted into a stitch-ready format (Process named Digitizing- Normally around £20-30 per design) so it can loaded onto a machine and stitched onto fabric. You will find limitations with your designs with this method as you need to have clear lines so complicated designs can look shit if done with mediocre machinery or when done way too small. Again, not going to spoon feed so you'll need to work with a studio to find what size works best for your design.
Now we have Vinyl and Digital, not going to go into much detail as these are bottom barrel techniques. Vinyl/Heat press is where you print your design onto vinyl and its put onto the fabric via heat application. It's much cheaper and tends to have no MQO but it isn't as durable and looks glossy since it doesn't actually get embeddeded into the threads of a fabric like screen printing does. Digital on the other hand is where you literally print straight onto your fabric via a large format commercial digital printer.
Type of garments: This one is super easy. Just decide what you want to put your design on. You want a heavyweight hoodie? How heavyweight? T-Shirts - Yeah great but what kind of fit do you want on your tees? Etc etc etc. Learn about GSM and for fuck sake please just sample blanks. Nobody in the industry is going to give you a list of what to use because it's gaurded information since it costs a lot of time and money to sample hundreds/thousands of blanks. Starting point of bottom end: Gildan, Fruit of the Loom, American Apparel and Sol.
Finishing touches: Custom nape labels/nape printing, hangtags/swingtags, custom wash labels, polybagging/folding, size stickers etc etc etc - More things for you to research. If you want bonus points when you're contacting suppliers then know what type of label material you want and what type of fold/stitch you want. You're welcome.-----
Blanks, Studios and Manufacturing Process itself
Locating suitable blanks is not difficult, the same general brands have been used for years by brands of all tiers; The hard part is finding a supplier with access as most of the time you need wholesale accounts to access/purchase, and I'm sorry I don't care if your bot has 27,000 followers on Twitter but that ain't enough for a multi-million pound garment production company to give you wholesale access. You want to start by knowing what type of items you want, what fit and what quality. You can then go off on your own and locate them via somewhat intensive Googling (lmgtfy: t-shirt wholesale lol) or you can find a studio/supplier and use their contacts. 90% of studios will cater for you and help you out so they can keep you on as a returning customer. You'll be surprised to know that even the classic Supreme heavyweight 450gsm Canadian cotton sweatshirt is an easy to find blank too and actually wasn't solely a cut/sew piece (Lesson: Cut/Sew refers to the process of creating fully unique/bespoke clothing, normally done via an actual factory - This is expensive, high MQOs and is simply not worth your while unless you're an actual brand or you just have money to blow. If either of them fit you then simply google "Cut and sew production" or whatever and you'll find more than enough). The cut/sew process is much more rigorous and costly due to the fact an actual factory is producing the garment, to your specification, this includes exact measurements for each size and exact fit. MQOs for this kind of work is in the thousands to produce the actual blank itself, unless you either have a friend who works in fashion design (Students have the capability and access to machinery in that respect) since the chances of you (Speaking in general) wanting to produce a huge volume of a fully bespoke item of clothing is rare especially when you can source blanks of any fit/style via the internet, hell I even know of *major* brands who source all their blanks directly from Alibaba/Aliexpress etc at around 8-12USD a piece for pretty decent items but the issue there is importation and quality control unless you're ordering enough for the factory there to want to work with you privately. Blanks aren't just limited to hoodies/tees etc, you can find pretty much everything out there, from full tracksuits to puffer jackets.
Now I'm going to touch down on studios. This is where you take everything you've discovered above and you email a studio who have the screen printing carousel or embroidery machines etc and you give them a lowdown of what you're after, including garments, size breakdowns, colour breakdowns, finishing touches required and any questions you may have, as stated above you can even ask them if they have any recommendations for X or Y from their usual suppliers, or if you find a blank you want you can ask if they currently have a wholesale account with said brand. Alternatively, some studios allow you to provide your own blanks but this isn't too common nowadays due to quality control and stock issues - If you order 100 hoodies and 8 get damaged during production you're going to have to send them another 8 (or more) to rectify it; It's long and they ain't got time for it. Local studios do fucking bits and are often overlooked, 9 times out of 10 they have shit websites and don't look special but they take care of you and often bend rules since they appreciate the work, I strongly recommend reaching out to any local companies and seeing if they can work with you, or you can use bigger companies if you wish. I don't really think I should name any as you can literally Google "screen printing" or "t-shirt printing" and you'll get results. Again, not spoon feeding as it's all subjective/trial and error. Put the work in and find a company that you fuck with. Over the years I've used around 14 companies with 4 of which being my regular go-tos simply because they were great with me and were happy to bend rules to keep me happy.
The actual process then takes normally under 2 weeks depending on quantity. You will need to green light before it goes into production, from that point onwards whether you don't like the outcome or not it's tough shit - This is why it's important to know what you want and give it in detail to the studio. Always ask for proof-copies of your final design on scrap material so you can verify you're happy BEFORE it goes into final production; Common sense. Once done the garments are shipped directly to your door for you to fulfil orders and ship out - If you handle a large volume of orders and you simply can't be bothered to do it by hand you then Google eCommerce fulfilment and research that side of the game.
Brief lesson on IP/Copyright/Trademark; You cannot produce nevermind sell anything which includes a trademark/copyrighted image without explicit permission from the individual or company which owns the IP. This means you cannot use a design featuring the Swoosh regardless of the Swoosh itself being a key part of the design or not; If you don't own every single part of the design then simply do not print it. It's that simple.-----
I think that just about concludes the general breakdown of producing your own merchandise. I'm going to leave a few links below for reference in terms of blank sourcing and studios; This includes professional studios I've used in the past along with actual wholesale companies which sort numerous brands of various quality, including sub 500gsm sweatshirts. Stop paying kids a 80% mark-up to produce your merchadise on Gildan Heavy, it's fucking exhausting to see.
https://www.merchasylum.co.uk/ | https://www.octomuffin.co.uk/ | https://blackwaterstudios.co.uk/ | https://www.buildyourbrand.de/ | https://shop.ralawise.com/ | https://rueporter.com/ | https://www.firelabel.co.uk/ | https://www.culturestudio.net/ | https://www.awesomemerchandise.com/ | https://www.woveninc.com/