Back when I was a youngin' in Nowhere, MN, my Dad would take me to open gyms* and we'd practice doing hitting drills with things that wouldn't damage the floor like plastic golf balls, tennis balls, etc into one of those pop-up golf nets using a thunder bat. There's lots of fielding drills you can run with tennis balls that won't hurt the floor too.
To practice pitching, we'd lay a bunch of mats on the floor in front of one of those fake falls gyms have to divide up gyms into smaller sections, then if he missed a catch, it'd just go into the plastic wall and not hurt anything.
*The school district would rotate which schools opened their gyms on nights and weekends during the winter to give kids a place to go. I think there was a nominal fee, 2/3 bucks to go per person. The city I live in now does this too, don't know if it's a national thing.