EDIT: the design of this battery was a failure in several ways, however there is still good information regarding the techniques used to build a battery. Read at your own risk 
Ok dudes, @rafaelinmissouri asked for a battery building walk through, so I said I would document my next build… although alot of this won’t be relevant to a standard pack, most of it will. On to it.
Start with your cells and line them all up to check the voltages. Most of the time the cells I get are between 3.41 - 3.45. If there is a cell that is way different, don’t put it in the pack. Put it in a torch, or a vape, or a dildo, whatever.
Glue those bastards together. Many people use hot glue. Many people use silicone. My personal favorite is polyurethane. Sika 11FC 
Once the cells are laid out, i like to lock them in by screwing down some timber.
I like to put the cells in a square jig and lay out each p group and then flip the next p group the other way around. There are 2 reasons for this.
Firstly, it makes it easier to see where to stop gluing (you only want to glue together single p groups at this stage)
Secondly, there is a ring around the top of the cells that is the slightest amount thicker than the rest of the cells and if you butt them all up together, they don’t squash up well.
Insulate your cells. The little rings of fish paper protect the negative outer circle at the top of the can from your positive connections. They are an absolute must have in any pack.
I have found a good source that has strips of 9 rings joined together, it’s definitely a time saver. You can find them here : https://a.aliexpress.com/MqRnPULW
Keep the leftover bits of fishpaper, as they do come in handy. Often if I am folding nickel down the side of the cell or I think there is a small point that might receive a little more abuse, I will stick one of the little circles on that point and tape it down.
I like to fully wrap the p groups. Cut the paper to length making sure that you overlap by at least 10mm just to make sure you don’t fall short.
Start to wrap by centering the paper on the group and then fold around each side. This helps everything stay nice and square to the pack.
The paper I use comes in a 65mm roll, but there are other options for different cells too. You can find it here : https://a.aliexpress.com/sEkzB9Ne
Design your connections. I generally have a good idea of how I’m going to build a pack, so I usually wait until now before I finalise it. It’s nice to draw your + and - on the packs and arrange them in the space where they are going.
Take a photo, draw your connections. I went through a few iterations for this pack before I settled on something I was happy with. There is no ‘best’ way to build a pack, every pack has different requirements so I will run you through a few of the things you should consider in your design…
Does the board flex?
If it does, your connections will need to allow for this. Silicone wire and braided copper are good options for flex packs.
How many amps is your pack going to push continuously?
You will need to know this to size your series connections adequately. There is a good thread here: Conductor Current Ratings [SRO]
Where will you run your main terminals and balance leads?
Be sure to allow enough room for your mains and balance leads. These may be on top or beside the pack or both, but it is an easily overlooked part of the design.
In my case, the board doesn’t flex, my connections need to allow for modularity and I have heaps of room to the side of the pack to run mains and balance leads. Great!
Once you have figured out your design layout and connection details, you should be able to determine the length and amount of nickel strips you need to cut. In my case, it is 80 strips at 50mm long.
I need 8 x 50mm strips for each p group, so I mark out 8 x 50mm intervals on my bench top.
I keep the nickel roll with one loose zip tie around it and can easily hold onto the zip tie while reeling nickel off the roll. Line the nickel up with the marks on the bench top and mark them.
After you’ve marked the 8 strips, cut them off as a group of 8 and repeat until you have your 10 strips of 8.
Cut the bastards up. Get your corner chompers ready. If you don’t have corner chompers you can easily round your corners with scissors. Or just be a rebel and keep your sharp corners (i don’t condone this type of rebellion)
All rounded. Be super careful of the little offcuts of nickel. Those motherfuckers are SHARP.
Time to weld. I am building this pack with bus bars so there is no need for me to weld a strip across the top of the cells. The bus bars will carry both the parallel and series currents and my design requires that these busbars sit on the sides of the cells, not the top or the bottom. So therefore I am using tabs.
To save on the amount of soldering i would need to do for 4 tabs, I decided to weld my tabs together. I used and offcut of the insulator rings we saved earlier and traced it onto a piece of glass…
Don’t weld on glass 
it pitted after the first weld. I switched to a plate from the kitchen. It held up better but there was still significant pitting.
The problem with the pitting is that it can create a hollow underneath where you are trying to weld. If there is air below your weld, you will likely blow a hole in the nickel.
When welding to cells, I like to tack weld everything first. I try to only do one set of welds per cell per run. This is to minimize the amount of heat transferred into the cell.
I think that 3 sets of good welds per cell is ample. But they need to be good welds. A good test is to do one set of welds tacking nickel on a scrap cell (or a good one, but you’ll have to clean it) and then try to pull it off. If you can pull it off without tearing the nickel, you need to bump up your weld settings.
Next will be soldering but my phone is about to die…
