Pinball.cool is a game that allows you to design pinball machines, marble runs, pachinko boards, and pythagora switches.
If you login with a Google Account you can save and fork your creations, but it's all available to play with without doing so. There are built-in tools for creating walls, flippers, bumpers, conveyor belts, turn hammers, ball dispensers, score targets and more!
Press B to drop a ball at the mouse pointer and use the left and right CTRL keys to activate the flippers. You can create blank boards, drag in your own creations or fork one of those already there. It's a lovely idea and fun to play with, so please leave feedback in the forum thread!