It's neither pretty nor fancy, and it's made of garbage. Yet a recent addition to the plethora of piggy banks available to the nation's would-be penny-pinchers is proving particularly popular with hard-core fans of the Japanese saying that goes: "Kane no aru tokoro ni kane wa nagareru (Money flows to where money is)."

Dubbed Cashball, the grayish-green sphere introduced last fall by a Toyama-based waste recycler is minimalist in design -- having no more than a golden string round it by way of embellishment. But it's not the shape that's selling Cashballs -- but the fact that it is made entirely of shredded bank notes.

According to Cashball makers Ishizaki Industries Co., who get the shredded notes fresh from the Kanazawa branch of the Bank of Japan in Ishikawa Prefecture -- the inspiration for their unique piggy bank came two years ago, when employees noticed a visiting BOJ official carrying a ball pen containing shredded banknotes.

At first the folks at the company, whose other products include biodegradable flower pots made from used tea leaves and coffee grounds, simply marveled. Then they wondered if they could apply their molding technology to the shredded satsu.

Company official Soichiro Shimizu said that the piggy bank idea was initially "kind of an inside joke." But when they tried to turn the joke into cash revenues, they found that serious talks with the BOJ were required.

While the central bank routinely collects tons of old and damaged bank notes, shreds them and then has waste-disposal firms come to take them away, Shimizu said it is very picky "for security reasons" about how the waste is handled.

"It took nearly a year before the BOJ agreed to hand over the shredded notes," Shimizu recalled, declining to comment on the financial terms of the deal. "Every minute detail had to be spelled out in our contract, like which retailers we would sell the product through, and how we would store and transfer the shreds."

But for Ishizaki Industries it was a picky process that is yielding rich pickings. To date the company has shipped 16,000 Cashballs, a figure far in excess of its initial projections. Now a second project is in the works, and the company hopes to market a clock made of old paper money by early summer.

Why a clock? Ask Shimizu and he quote another saying: "Toki wa kane nari (Time is money)."