I toyed with this idea when i saw the price of the sausage filters too
But after talking to my local tuning company he reckoned that no matter how well i made it it would produce less power than with a sausage filter because of the restriction it would cause, it wouldnt be much, but a restriction all the same.
So i went for a sausage in the end as i need all the power i can get as im only using a humble cvh! until this winter that is
Be careful with the cheap cone filters though if you go down that route, some of them are very restrictive and some are the opposite and let dirt through!