Yes used to cut up all sorts of veg and also treats for my TB mare .......can't give to my cob as gets to frustrated with them and beats the cr*p out of them!!!!!!!!!
I only use pasture nuts in mine but they are the red snack a balls with the yellow lids and anything big won't go round the edge of the partition inside the ball. I have tried cool mix but it's too sticky. I know you can get other makes of snack a ball that accommodate bigger pieces like chopped up carrot.
I put the Gold Label Olewo pellets in mine - it's pure (dried) carrot! I haven't tried them personally but they come highly recommended by my mare! It has recommended daily feeding quantities on the tub which I stick to - i.e. I'm careful not to over-feed it.
I put cheap high fibre cubes and those little bits of dried apple- also, why didn't i think of using the other side! I once bought some crunchie things which were to big, and actually cut them all up into little pieces so they would fit!!!