I started with the default attachment shape created previously and built onto that,

The simplest solution was to have a hopper (originally sized to fit a single trough’s worth of feed) with a servo driven lever on the bottom to allow it to be emptied.

The MG90 servos used in the robot arm seemed reasonable powerful so one was designed into this model.

The challenge was to design the lever in such a way that the horn attached to the servo was embedded into the lever so there was no gap with the hopper hole

The design was 3d printed and worked exactly as intended.

Here it can be seen being tested with a simple servo tester.

We used a breakfast drink container rather than 3d printing a hopper. It was though that it would be smoother (which it was) and could be cut to the right size.

In testing it seems that a full bottle can hold more than enough rice to half fill each of the three containers in a single run.

Weight wise the attachment seems strong enough to hold it and the robot seems stable as long its not driven and stopped too quickly!