Question 2...about my cats sickness and fur?

hi again,thanks to you all for your advice about my recent worry.my cat has started being sick about twice a week,but is very happy and content.after all your responses i am now thinking that it is a fur ball as suggested.she has been wormed very recently and is constantly preening and cleaning herself.....my next question is how long does it normally take for her to bring this dreaded fur ball up and...ok..you might think im a little bit daft here but here goes...will it look like a ball of fur!!!!!!!..is there anything i can get from my local pet shop that could help her....any help most welcomed,thanks,susie