very neat mate :+1:
I haven’t tried turning flat tops to button tops, but if I did, I would use the same method I use for making buttons for positive contacts on drivers:
1. Take a piece of sheet copper and cut a small disk using metal scissors.
2. Place cell vertically in vise.
3. Apply solder paste to top of cell
4. Place copper disk on top of paste
5. Use a toothpick to hold disk in position so it doesn’t shift while applying soldering iron to top of disk. The instant the solder melts remove iron.
6. If necessary, apply a second disk on top of the first for a taller button.
7. If necessary use a handfile and possibly steel wool to file the top of the disk completely flat and to remove any sharp edges.
I’ve when using neo 5mmx1mm or 1.5mm magnets. No need to glue or washers or any kind of spacer. Just center and load the whole assembly up. Most lights that need button tops have a non-conductive ring that surrounds the magnet.
I vote for buying button tops in the first place. 
Are there any instructional videos on how to add solder blobs without causing explosions for soldering non-experts?
It helps when you have developed some soldering skills of course.
But the flattop surface (of course) needs to be clean and without oxidation.
Do not sand the nickel plating off.
Use a hot iron of around 40 Watts.
Wet the tip with rosin core solder, put it on the flattop.
Add rosin core solder kind of between tip and top.
Add more when it starts to flow.
Move the tip over the surface of the top while adding more solder.
When it’s all flowed on the top (and you have put enough solder there), retract the soldering iron.
The solder will solidify in a nice dome shape.
This all should take no more than 4 or 5 seconds !
Maybe you can practice on tired old laptop pulls.
Good info Jerommel, thank you for posting it. :+1:
My goal is to make mine look as perfect as yours do in your pics up in post #4. 
Other - I prefer to go from house to house and explain the peril their little battery souls are in if they don’t convert to button top ism
I use piece of solid core wire and bend it into a ring and give it a tap with a hammer to flatten it some. Then i just solder that to the battery.
Nice one ‘Tjhosan’. I never thought of that, thanks for sharing.
Thanks for the instructions!
Have you tried doing tail cap amp readings with & without magnets ?
I used to use magnets but after finding that on an S70 on turbo running 2 x Liitokala 26650”s with magnets I was losing nearly 0.5A.
It may be of course that the magnets I was using had pretty high resistance but because of that I quickly over came my fear of solder blobbing cells & now solder blob if I need to turn a flat top cell in to a button top :+1:
I’ve seen magnets dent my cells .
not a fan of magnets
Solder blobs are simple …Add flux first then load up your iron till the solder is almost dropping off …it takes about a second to do .
Kicked myself for waiting so long to do it .
Seems like I was always hunting for a longer cell for lights that didn’t have a spring …messing with magnets or buying protected cellsbecause they were longer was just dumb .
+1……. I was in the same boat as you Boaz until not too long ago. I detest magnets….
While I just received 10 flat tops, I was in need of a solution.
A quick search of the forum, and here I found some nice ways of getting the task accomplished.
Excellent topic, ALL. Several great solutions!!
Thanks to all who chimed in.
Update:
I just did all of mine. Works as explained.
I used to use solder and a washer of the right size, put the washer in place and then solder into the hole in the middle, it gives more strength than just solder,
Now I just buy the correct batteries with buttons .
Not many people use spacer, i dont know why
There is battery store at my place. And they have service convert from flat head to button head, 1$ for every 5 batteries
The result is good(at least to me)
I use some magnets and a little bit of glue to stop them sliding to the side.
Made a couple of these.
I just drop one in between the flat tops. Usually 2 batteries and usually the first battery in doesn’t need any help, at least in my flashlights.
The disc keeps it centered in the flashlight tube. Solder blob in the center. These are the thicker ones. I use the thinner ones most often.
Not a good solution for everyone but works for me. YMMV.
These are for 26650 sized cells
+1 Agreed. I’m inspired looking at these guys solder pics.