What are some good at home tennis drills you can do with your racket and ball?

You might enjoy this

Yarnlady’s link looks interesting. I used to have a rebound net, I bought it 2nd hand for $100.00 have no idea what they are new or what they cost now, but it was great, you could hit as hard as you wanted and take it on the first or second bounce to return. I wish I still had it.

Well, indoors the only one that really comes to mind is the bouncing the ball on the racket one. Just perhaps once a day bounce it up and down a hundred times. A hundred using one side of the racket, and a hundred using the other side, but keeping a continental grip/forehand grip.