This week in design: AC signals are so much cleaner with PCBs than on a breadboard! Here are some boards I ordered from Osh Park for 60 cents per three boards. (Don't worry, I batched my order into a bigger one to make sure Osh Park didn't lose money on shipping.) The PCBs are still bread-boardable, so there are no downsides (except the wait time).

Unipolar rectifier for a square wave

Bandpass filter, RC