A few weeks ago Erwin who also lives in the same apartments was muttering about a mirror for his road bike. He is quite a keen cyclist of the racing bike type and he was having issues with not always being able to see what was coming up behind him on the road. Normally this would just be a quick trip to Cebu city but that's not happening at the moment. So I thought I'd take a look at it from a 3D printing angle.
I did look on Thingiverse but there was nothing that quite fitted the bill so what ever way I went there would be some design changes required.
I did find a small 40mm blind spot mirror in the motoring section in one of the local hardware stores that would work for the mirror but but nothing that would work on drop handle bars but it was a start.
I did find a bar end plug on Tinkercad that would be a good connection and using that as a base I designed a hanger for the mirror in Tinkercad 
The orange bit is for the mirror, the pink bit is the connector and the yellow a modified bar end plug with connecting boss. In total it took about 3 hours to print in PLA at 40% infill.
All together it looks like this.
And it fits Erwins bike like this.
Thanks to Linda, Erwins Misses, for the photos, it was late when I finished printing and I forgot to take any.
I am quite pleased with the result, but there was a minor hiccup, when Erwin broke one of the bosses fitting it. No big deal, I just reprinted it with a higher infill to make the part stronger which only took 20 minutes or so to sort out.
All that waiting now is for him to go for a test ride :)