Here's The Brat's first PCB layout. U1 is an LT3580 in the leadless
DFN package. It's working as a Cuk inverter, making -2.5 from +12.

This is a very cool part. One resistor sets the frequency and one
resistor sets the output voltage, and it's smart enough to get the
feedback right whether it's an inverting or non-inverting converter.

The whole thing works!

John