I like your idea, but I was told to never accept wooden nickels!

Metal is more durable than paper or wood.

More specifically, I don't recall the exact frequency but I think paper currency gets replaced (mostly) as frequently as every few years or so (look at your wallet, do you have any bills from the 80's?)

In contrast, think about how long currency circulates, I routinely get change that is older than I am (nearly 30).

Generically coins are used for small value transactions (which can be vending machines etc)

Currency is used for high value. Paper has the major advantage of being lightwieght and easily portable whereas coins have the advantage of being smaller and durable (but heavier).

Consider as well that the smallest "unit" we use would determine the lowest price generally available - so if all we had were $1.00 and up units, parking (even for 15min) would be $1.00... (and gumballs would be the business to be in)

Coins are round because they're easier to sort.

Not my idea, but worth repeatingLOSE THE PENNY COIN and the ONE DOLLAR BILL:

Start rounding to the nearest 5 cents.Stop producing pennies.In cash drawers relocate: nickles into penny tray, dimes into the nickle tray, quarters into the dime tray.Place $1 coins in the quarter trayOne dollar bills no longer printed.Shift folding money one slot, opening up slot for higher demoninations or $1 coin rolls.

Plastic bank notes can be found in Europe, Australia, New Zealand, Indonesia, Singapore, China, etc. Durable, long lasting, extremely difficult to counterfeit. The first notes appeared in Australia during 1988.

As for coin, many currencies have dumped denominations less than 5 cents and introduced $1 and $2 coins. It costs money to handle money, so why deal with small denominations?

Coins will no longer jangle and make holes in your pocket. Aren't we forgetting the concept of 'future money'? The folding bills of today will be replaced by digital money. Think of a credit card with no visible number to steal or an ATM type card requiring a bio-metric pin number, an eye-scan or voice print, thumb print or similar. This makes the card impervious to theft and loss.

Many people in Europe even use their cellphones to make purchases at vending machines by calling a toll free number and a debit is billed to their mobile phone bill.

I see the privacy pundits ears are burning, since your purchasing habits may be tracked. These records may have to be sealed to protect the shy.