Olikraft bobbin winder centers

My wife wanted a smaller diameter center for her Olikraft bobbin winder in order to create more compact balls with ends of threads. Posting here in case anyone wants this too.

The original is 40mm diameter. Our first attempt was 20mm but usage was mixed. It mostly works but the thread tended to get stuck winding at the top of the resultant ball from time to time instead of neatly winding around the ball it's building up. I printed at 0.15mm and the layer lines made it somewhat rough such that the thread might be getting a bit caught on it and perhaps smoothing it off would help but we haven't tried that.

The next attempt was 30mm and the wife verdict on that one is that it’s great. No difficulties with winding and creates more compact balls.

Update. My wide says the smaller one is great for small leftover bits of yarn. And the medium sized one is still going great.

Update 1/16: Added one that you can friction mount a standard bobbin to.