This part is mounted in the top panel blind clamp and causes the blinds to catch the adjacent blind when being horizontally extended or retracted.

The original part broke after ~5 years of use and the manufacturers weren’t helpful in sourcing a replacement so I made one myself 

These blinds are made by the Australian brand “Kresta”, but I’d be surprised if they’re not common across lots of different brands.

The original ~2mm countersunk screw to fix it in the track is re-used.