Well those are some very affordable steel bar ends similar to the one in the picture below:

I paid them around 6 dollars. The good thing about this design is that normally they can't go around curves on my main bar but you can use some tool to make the opening wider just enough so that you can go around the curve. I used hammer and inserted angled part into the opening of the bar end, then I pressed it into the opening (it was some force indeed) against the floor, bar end got a little bit wider so I could navigate it around the curves on the main bar. Later on I used the supplied screw and tightened the bar end so it returned in its initial state. I believe this is easily accomplished with steel bar ends and the steel is more flexible and resilient to aluminum to bending and deformations so you won't damage bar ends.