I own the Delta Children City Street LX Side by Side Stroller. One repeated complaint about the stroller is the low handlebars. They force you to walk very close to the stroller, so I kick or scrape the stroller about half the time. 

I saw other parents who had attached bike drop bars to their strollers to increase the height and allow them to walk further behind. I purchased the Origin8 Compe Lite Bar End and Schwinn Ergonomic Comfort Bicycle Grip. The opening in the drop bar end is too large to grip the stroller handle, so I printed some bushings.

I printed these in PLA, 0.2mm layer height, 3 walls, 15% concentric infill. The bushing is slightly longer than the drop bar bearing surface to try and distribute the clamping pressure.

I was worried that the PLA would not compress enough to form a tight grip on the handlebars, but they seem to be solid. If they start to come loose, I will try again in TPU or another flexible filament.

I have also included a test print. I used this to ensure that the inner diameter matched the stroller handle.