Examples from the Web for soap-box
Russ and Laddie, riding in their soap-box dog-cart, came along the public road.
He came when Russ called him, and he wagged his tail when the boys showed him the soap-box cart and the harness.
Manners was back on the soap-box, still as a sphinx, and smoking his pipe.Aladdin O'Brien|Gouverneur Morris
It was very little happiness that the boy on the soap-box was getting out of anything, that gray December afternoon.Asa Holmes|Annie Fellows Johnston
On her feet she would barely have reached the rim of the great dish-pan, but on the soap-box she did very well.The Very Small Person|Annie Hamilton Donnell