Compositional chops - melodic variation

Melodic variations

A photo of them is linked above.

Also! Check out the Rachmaninov/Rachmaninoff variations on a theme by Paganini.

There are quite a few, but start with variation 18. This sounds NOTHING like the original – but is very effective.
variation 18

If you listen to others, consider what you think the variation technique he used might have been.