As far as I'm aware no-one has made a pack with only flippers to download.
Assuming you mean DSL 2.1 and not 3, if you're looking for IRL style designs Live Designs has some good flippers in it. Here's a link:
https://gametechmods.com/forums/index.php?topic=10632.0Keep in mind you'll need to do some messing around to get one or two of the bots to work, but this should be explained by the ReadMe file Badnik provided. Also, since this is a full AI pack, I'd recommend getting a clean copy of DSL2.1 and installing the pack over that.