well for more diff friendly indoor fun you can make some ramps out of cardboard boxes
. just turn it so that it's on it's side and cut one hole side but don't cut the bottom. then like roll the side you cut so that it's nice and beny. then just tape it to the bottom piece and poof you've got a nice kicker.
here's mine
with the tall brown one i can jump over my couch with a 10 foot run up to it
. and the really wide small one is for outside mostly so i can hit it full speed