The Bamboo suit, or "Bam" as we in the US call it, is sometimes known as String of Cash. This suit is based on actual strings of cash. In the early 1900s, and probably for years before that, Chinese coins were carried on strings put right through the hollow center of the coin.
I just came across a photograph taken of real strings of coins, and you can begin to see how these strings could change into looking like bamboo stalks seen on Mahjong tiles.
The photo below shows workers putting coins on hemp strings, and the piles of strings of coins on ropes on the table below.
Photos are found on page 51