Helmet. If you don’t have one, get one before you build.
What do you want out of your board? Range, top speed? What kind of environment are you planning on running on? Is it all smooth road, sidewalks, cracked sidewalks, offroad?
Answering these type questions will help get you a good response.
And make sure you have a helmet
after that, gloves, for real, with wrist guard
10char
I’d personally go for the DV6 because it’s been very robust and powerful for me. You don’t need a ubox that’s totally overkill. In fact you could probably get away with a dv4 and save money since the build is pretty low powered right now
Keep in mind you’ll need a loop key though
I know someone selling @BigBen fiberglass enclosures for the Hummie deck in the US. PM me and I can put you in touch via Telegram. I believe he’ll sell you one for $50 + shipping, but it might be a bit higher.
As far as the battery, the Mboards 12s2p or 12s3p should fit, but it could be a little tight on width.
I would recommend the MakerX DV6 Pro out of those 3 ESCs. They can push the most motor current and are known to be highly reliable.
I see you have a complete drivetrain picked out from TorqueBoards. While they do have quite a deal going on, their trucks are known to bend, and don’t expect any customer support from them if you do have issues.
As others have said, protective gear is a must. You can often find deals on high end mountain biking helmets on Craigslist or Facebook Marketplace, especially by searching nationwide. Many people are willing to ship if you contact them. I recommend @XBoard gloves for a good balance of protection and dexterity.
This starts off great, but you immediately got into “battery” without knowing how much space you have.
Do yourself a favor 
Try to make sure everything will work together, because this is a very common problem you will encounter.
Also this:
The worst time in the world to not have a helmet is right after you got done working on a mostly-built-but-now-rideable awesome vehicle and of course you need to take it outside and rip it down the street RIGHT NOW
The Mboards 12s2p and 12s3p batteries should fit in the Hummie cutout. The cutout dimensions are 585mm x 145mm. The Mboards batteries are listed as 146mm wide, so some dremeling may be required, but it’ll fit if you’re lucky.
As far as height, a BigBen single stack enclosure has 25mm of vertical space and a double stack has 37mm. The Mboards batteries are listed as 1” (25.4mm) tall. I would recommend going with a double stack enclosure unless you’re willing to add a gasket to the single stack one. You always want a few mm around the battery to add vibration damping.
Gaskets [for space-filling purposes] are evil IMHO
It means it wasn’t engineered well.
I mean, you’re correct… the BigBen enclosures were built for 18650s, not 21700s, but solving the problem via gasket is a lot less work than making your own fiberglass enclosure for most people.
I thought so too, until I actually tried making fiberglass enclosures.
As long as you don’t care how good they look, or how messy you get, making fiberglass enclosures that work well isn’t hard at all.
this is actually the difficult part, it’s all mental. It’s literally in your head.
I’d also suggest that it’s not hard, but just lots of work.
If you do it using correct PPE, materials and process it’s definitely something you can learn to do reasonably well.
Read lots before you start. There is heaps of info on here and that other old forum.
If you value your time, and aren’t doing it as a means to also learn a new skill, buying an enclosure is a better proposition.
I’m intrigued. Someone who has a stock of them?
Nah, just someone with a 3 Hummie decks and enclosures to go with. I bought one of his decks without an enclosure so I figured it would be good to promote so he could even things out again. Here’s the picture he sent:
Oooof, they gonna be scratched like that. Wondering what the white enclosure is.
For anyone wondering, although the single stack enclosure was originally built for 18650s it fits a 12s3p of 21700 really well.
Archee?
Yep they’re his. I don’t think he has an account on here.
I don’t think so either. He’s a good dude though
Or just don’t try to catch any falls on your hands? 
I’ve only ever gotten super minor scrapes on my hands during falls. No burns at all unless it was a super small 1st degree burn that I forgot was even there 
Now, if you live somewhere cold, then I do suggest you get gloves so that you don’t let your hands freeze and can’t use the remote. no one makes sk8 gloves that fit me anyway and I refuse to pay way too much to get gloves that don’t even fit. Never really had any problems without them during my many falls
If you wait to get a helmet, just go buy one from a local bike shop. Those are still very common and it will provide way more protection than the skate helmets will. (unless it is a full face helmet marketed to esk8. Those ones, if they exist, will provide enough protection)
It’s all in how you fall and unless you’ve spent time forcing your body to behave against its nature your hand is “coming to the rescue” when you go down.
35 years after a 3-4mph fall coming back down a ramp and the carpal bones of my right hand still pop out of place if I don’t exercise the muscles regularly (ligaments all got destroyed when my wrist shattered).
Still, will take a helmet over gloves everyday of the week and twice on Sunday. But would rather be wearing both
Ahh it seems my “cringey” teenage years might have worked in my favor then. That is the only time where I actively tried to change my reflexes. Used to go to the park and run on the loose boulders placed in a drainage ditch even for fun.
I fall elbows and knees first and then the base on my palm hits the surface at the very end or not at all. I’ve never owned or used elbow and knee pads either and yet that is still how I have fallen almost every time. 
Exceptions are when I fall backwards which means directly onto my ass. RIP my already damaged tail bone Or one time in the mud it resulted in a baseball home base slide of a fall somehow. Still no idea how that happened tbh
I do know how annoying it is to have shit connective tissues. Sometimes it can help you avoid broken bones but other times it is just annoying. Joints are weak in rotation leading to the most common breaks, but strong in all other cases Wrists would suck more since there aren’t a ton of muscles in the area you can build up to add more stability like there are near the ankles. Or at least it is easier to build up muscles in the legs
