i find the biggest issue is that strong magnetic contact will pull the magnet off - so when I do similar mods to this I actually coat the entire thing in a fine layer of UV epoxy/glue, to both reinforce the adhesion and more importantly reduce the magnet’s grip strength slightly by making it easier to slide off surfaces without pulling the magnet off your light. it also smoothes out any sharp corners // 90 degree angles so the magnet is less likely to get caught on things when inserted into a pocket/bag etc
I bought the FW3A tailcap (without the magnetic ring slot) from @tristech. Shipping was fast and it fits perfectly. Super happy with this add-on.
Received my order today. It’s perfect and it’s the way the light should of been made in the first place. The fw3a was basically useless to me because of the beyond way too easily activated tail switch. Accidental activation is not a problem now and the light is still easy to use.
Can someone post some pictures of the blue/grey FW3A with the Grey or Grey/Silver cap on? Just want to see what it looks like. The purple filament looks like it would match pretty good. Very interested in this.
glad to hear. and yeah, I totally agree. I don’t understand how folks can edc/carry it at all OOB.
sorry for the delay- busy weekend! the purple on my fw3a looks a bit lighter than normal (in the couple tiny places you can see it) bc i deanodized my light - it’s not 100% perfect but i think it will match pretty well. probably should have deanodized after getting the purple filament + taking a capcrown pic oh well lol
edit: installed on the fw3a is the silver color, in the foreground is the color of the grey, black, copper (this one is a weaker plastic the others are quite strong), and purple (the grey inside is the protection insert for shipping) filament/plastic
thank you tristech for posting the stl
now I’m not afraid of my FW1A turning on inside my pocket 
Sweet! If you want a stronger hold, you can always make the bottom layer thinner or just sand down what you’ve already printed. I started printing with eSun PRO pla+ and it’s incredibly strong (has survived 3+ 4-5’ drops so far).
Also, I’ve been looking for a stronger ring magnet (that banggood one is mediocre) so lmk if anyone has a source for a 20mm diameter 2mm wall 4-5mm height magnet!
edit: ~2mm wall, can be a hair bigger
Bump.
I have successfully got the Bangood's Magnet to stay in place via a thin strip of Duct Tape around the outer circumference of the Magnet.
I used my pinky finger to set the magnet into place.
I had trouble removing the second one of these on my FW3A. I did not use the correct tool and it shattered on me :(. Then removing the second one, using the wrong tool again, I ended up removing it suceesfully, but damaged the annodizing. Next time plastic tipped tools to avoid damaging finishes :).
glad you got it working but i’m sorry to hear about the tribulations!
I designed it to hold securely without glue/tape - it’s possible yours was scaled a hair wrong - but more likely:
the QA isn’t very good on stuff like magnets from banggood. they may have sent you a slightly different diameter magnet than the ones I bought from them via the same URL a couple years ago.
I redesigned CapCrown a little bit ago because I wanted to use a larger/stronger magnet that could also be sourced locally (from the US). I made a post about it here
I also have two GITD filaments, but they won’t be as strong as the eSun Pro PLA. I’m surprised you were able to shatter that filament - I have yet to break one despite several drops!
edit: also, I tweaked the scaling of the designs and got a new printer. they hold quite firmly/snugly but I’ve still been able to get them off with my fingernail. I wasn’t able to do that on earlier iterations.
anyway if you want to try the new design i’ll either double your next order at no extra charge or give you a 40% refund, because i feel bad you had issues. just write which you’d like in the text box (if you order again). cheers!
Thank You for the work You have put into these.
I suspect I got two of the first generation ones, One Grey(user destroyed) and the Blue pictured above.
I will elaborate the word shattered, it did not shatter from dropping it, I shattered it bit by bit using the wrong tool. I did try pushing and pulling it off before resorting to force. It broke along the thinnest part between the diamonds when trying to leverage it off with a jewelers screwdriver. The nubs on the first ones really hold on to the groove of the tailcap! 
If You would like me to measure the Bangodd's magnet's circumference I have, just let me know.
yeah I’m curious what’s the OD on your magnets
Sure.
The magnet measures exactly 20.0mm
The 3D cap measures ~ 20.35 - 20.55mm
It stayed in pretty well and took a little effort to push it out once set into the 3D cap.
Is it that hard to put some rubber O-ring between the button and the switch PCB?