Caulk gun-like dispenser for whipped cream
My suggestion would be to use a piping bag. You can get various tips so you can change up the swirls and lines as you like.

Added by Jolenealaska:

I hope you look at the comments and all of the answers here. I have used both pastry bags (many times), and a caulk-gun thing once before I threw it away.

Disposable bags are not expensive unless you use a lot of them. And there is no clean up, 'cause you just throw them away.

The caulk gun looking thing is cumbersome and a pain to clean, pastry bags are a much better option. I realize that is a subjective thing to say, but there is a reason you never see pastry chefs using the caulk-gun thing.



Different tips give different results.



A coupler makes it easy to change tips or to use the same tip for different bags (colors).



Then you just throw the bag away and wash whatever tips you used.

Disposable Pastry Bags, 100 count

You can even just snip the end of the bag and not use a tip at all. You can do that with a baggie too, but a pastry bag will give you more control.