It may have been a typing error, but let's face it - a musical instument built into your walking frame makes a lot of sense. If someone made a zither frame it could be a good seller!
Then how about the Banjo stairlift (or bedwarming pan), plastic skinned bodhrans which could double up as a bedpan, kazoos adapted as asthma inhalers, the possibilities are frightening!
Quack
Geoff the Duck