The clip that came with my Shure BT-1 headphones broke after a few months (weeks?). I recently found the pieces and thought "hey, I can design and print a part for this".
After quite a few iterations I was happy with how it attached to the BT-1 but not happy with my clips. I decided to look on Thingiverse for a clip and found Clip Peg - General purpose. The "_Fast" version was perfect... except it was a bit big. You will find an embedded "_Fast" version of that clip in my .stl scaled to 75% in the X and Y axis (but retaining the full Z).
I used CA glue to attach the two parts (there is a track in the BT-1 clip for the clothing clip to glue into).
Admittedly, this is a fair bit bulkier than the stock, Shure clip, but this one feels secure (and if it breaks I can print another). I don't feel like I am going to loose my headphones (which I couldn't say for the stock clip which ever felt terribly secure). I tried scaling the clothes clip to 50% but was too small. For me, this size is easy to use and not overly bulky. Feel free to experiment!
Note that the BT-1 clip has a "bottom" with a small line of raised plastic inside. I believe this helps lock the clip onto the BT-1.
Use glue (such as CA) to affix the clothing clip to the BT-1 clip using the track in the back of the BT-1 clip.