Ive ordered SP10 Pro from Sofirn Official Store @Aliexpress , didn’t pay attention that the regular tail cap isn’t magnetic , didn’t order the separate magnetic tail cap.
(I thought it’s like HS10 or SC21 Pro, comes standard with magnetic tail cap)
Is it possible to add magnet to the regular tail cap? Well I guess “anything is possible”, “when there is a will there is a way” 
How feasible is it? Is it gonna be easy to remove the spring, stuck a magnet disc, reinstall the spring?
If you’re not fussy on the looks you could superglue a magnet onto the exterior of the tailcap. I did that on a Sofirn headlamp and it works well.
Aliexpress sells round coin shaped magnets of various dimensions.
you don’t have to DIY anything, it’s there to buy it separately.
But when I tried to buy one from ali, I got a not working one (it was to long, and didn’t make electric contact), the they sended me the wrong model one (the bigger), and then they sended me the wrong color one (black, and I wanted green, the first two were green). Then they give up, and just returned my money (aside the 0.8$ for the shipping the second one)
There are some updates on it later, I should update it again now, just didn’t botherd.
I was planning to install the magnet inside, but thinking about it I think it’s OK too to stick it outside using a strong glue, that way we can use larger diameter magnet and create a wider and completely flat tail, very good for tail standing.
Thanks for your idea
When I was ordering my SP10 Pro, I forgot to order that separate magnetic tail cap.
Now I’m still waiting for my SP10 Pro (in transit), I don’t wanna wait yet one or two more weeks if I ordered the magnetic tail cap now. And there’s the risk/possibility of Sofirn sending the wrong tail cap (too long/too big/wrong color etc…) , that will be phycologically disastrous.
I think sofirn should include two tail caps for each SP10 Pro (regular & magnetic). It’s easier that way for the buyers. IIRC Lumintop Tool AA 2.0 available in a package like that.
Thanks for sharing this info. That seems like a very simple magnetic tail cap construction.
Thanks so much for sharing the pictures and measurements.
Also for your YouTube vid
. That’s like a very fun toy with those magnetic tail caps
So you’ve got three different magnetic tail caps, right? The first one is green (wrong dimension), the second one is green (very wrong, it’s for SC31 Pro), and the last one is black.
The black one is the correct size, right? Does it have the same type of construction of magnet and spring as the first (the wrong) one?
I’ll be very grateful if you could upload pictures of the original (non magnetic) tail cap and the black magnetic tail cap. Specifically the inside of them, showing/comparing their springs etc 
I’m still considering the possibility to install a magnet inside the regular (non magnetic) tail cap.
Although, for practicality and usefulness, I think magnet outside the tail cap is actually better (larger diameter, completely flat tail, improves tail standing).
Yes, that’s correct.
Yes, the spring is just there (but it is strongly attracted by a magnet), and the magnet is on double side tape (and I can see a fingerprint of someone on it 
)
You will see it, when it will arrive, for the non magnetic. There’s some ring, that is holding spring in place, probably on glue. The magnetic pic are already uploaded.
I would recommend just buying a ring magnet, like the convoy one for the T3 (as it fits, and I have 2 of them), and glue it there… Then if it will still not be enough, just add next flat magnet in the center
What colour did you order? I’d try to help you but shipping from me is likely $7 -9. I have spare black sp10 magnetic caps (2).
That’s a good idea. Also Similar to magnet ring for Convoy S2+ , two of my Convoy S2+'s have that.
Red & Green. Yup, I’ll try the DIY route.
Thanks for your kind offer
This thread reminded me I hadn’t fixed this for my SP10 Pro.
I went a different route since I need the magnet AND the lanyard loop, something that is apparently a foreign concept to Sofirn. (Although some of their caps do have both so I really have no idea what their problem is.)
Mine is 3D printed.
Designed and modeled in OpenSCAD, sliced in Cura and printed on an Elegoo Neptune 2S in black PLA.
I do have two forms of red but I was proto typing in black, it was easy to just print the final in it.
2 stacked 2mm X 16 mm N52 magnets sit in an end pocket. Tooth washer was the right dia to catch the end of the body tube and provide continuity. Stock spring is free floating but upside down.
I might solder the spring/washer/magnets stack together. Then again I might not. It hasn’t been a problem with a loose stack in the SC31 pro cap I made 5 months ago. But it has onboard charging, this might get annoyed taking the cell in and out.
And as a side, here are some of the progression of test pieces getting the threads and clearances right.
Final product costs me less than a buck in plastic. All total maybe 3 times that including waste.
Its several hours overall in modeling, printing, testing, repeat, but its cool, it combines several hobbies I have, I hardly notice the time passing.
It was a lot less work this time around, since I modified some of the process and code used for the one I did for the SC31 Pro last fall. That one took weeks and 3 versions, to get right, but I was learning the machine and all the software then too. (I should note I am using someone elses SCAD code to generate the threads to measured ISO specs… that kind of modeling is still beyond me! )
A little smear of silicone grease is a way to adhere loose springs into tailcaps. I’ve got a BeCu spring held in place with grease in a light that has an aluminum tailcap. It hasn’t moved.
Nifty idea! Maybe if I can find some diaelectric grease, I should have some here somewhere… Although I don’t like the idea of the mess… I hate that stuff in places I Have to have it.
I’m considering just soldering the spring into the head, then it can be a solid conection at the tail. (SP31 has a springs at both ends, but I’m running it with a magnet as connection at the tail and just the head spring to take up tightening pressure/shock)
You can do it with the T3 magnet, you have space there for lanyard, but you won’t be able to easy change it, after you glue the magnet.
You would have to use some fishing line, to do it, because of little space you have there.
Thanks but I doubt I’d be able to trust glue/epoxy and the magnet on the outside of the light. And I think it eould be far too cramped.
I want a lot of room for lanyard rings, since its my only way to carry the light(I carry clipped off to a belt loop, Never in a pocket) I want as much full range of motion of a ring/clip. With a fully custom cap I have options for shape, layout, and everything captive. 
