Why do cats like to lie preferential on things that you are just using?
When she was little I had a hard time teaching her to not put her feet under the needle of my sewing machine. She likes to sit behind my machine and is watching closely. When it gets too exciting with all those pieces that are moving, she gives a hit with her paw.
After 5 years she starts to understand and is getting calmer now :-)
Now she is mostly only sitting on the pieces I need next ...