Minimalist Key Organizer

This is a super-basic minimalist Key Holder / Key Organizer that i designed and have been using for the last year.  I know there are many choices available, but i feel like this one has two great selling points:

1. Its as thin and small as i felt i could design it to hold multiple house and smaller keys and remain strong. It takes up the least amount of pocket-space while being strong enough for daily use...and i have been for at least a year. 
2. It attaches to your key ring with a metal D-ring that's positively attached to your hardware and keys (not a printed loop that could break more easily) that is also easy to source.

I think its beautify simple and easy to print well.

The Hardware: 
2x M3 machine screws - strong, but small enough to fit a wide variety of keys, the length is dependent on the number of keys, M3x16 fit 8 keys on mine. 
2x M3 nut (locking or standard) (keyholder v4.1_Side 2 - M3 Nut.stl)
Or -
2x M3x4x5 Heat set thread inserts (keyholder v4.1_Side 2 - Thread Insert.stl) - These are the ones i used 
1x D-Ring Hangar - these are in the small hardware section of many stores, they are for attaching to the back of a painting or picture frame or from amazon

To assemble: 
1. insert the M3 machine screws through Side 1
2. Slide keys over the screws, an even number on each side - or you will need small washers to take up the slack on the odd side.  
Tip: Turn the cut side of the keys toward the "inside" so that when closed the uncut side is exposed 
3. Place the D-Ring hangar tab screw hole on one of the screws, you can place in the middle of the 'stack' of keys or offset one side or another
4. Press M3 nuts into Side 2, or heat-set the Thread inserts into Side 2
5. Place Side two over the Side 1 keys and screws, hold together and tighten the certs into the nuts/inserts.  

You don't have to go crazy tightening, they don't really walk back out - but if you are concerned about it add a drop of blue thread locker.  The extra space added by the D-ring hanger tab adds a tiny amount of torsion across the side pieces which helps keep them secure.   I think in the course of a year, i adjusted the tightness of the screws once.