I love itHere’s one I made when my niece wanted to start tattooing. After the lining in multiple directions I had her practising different shading techniques within the shapes.
For myself, I downloaded loads of google and Pinterest images based on ‘tattoo outline’ and ‘tattoo stencil’ searches. I just kept repeating different designs with different degrees of lining challenge. Understanding lining principles is crucial, but after that there’s no substitute for doing and doing again.