Switchers
These things are everywhere. Sometimes called the unfortunate name of wall warts, but better called a DC Power Brick, or AC/DC adapter.
Calculators
TI's LM63460
Some manufacturers will have calculators in addition to the app notes that you can use. These are often based on excel/spreadsheet software. Reference: https://www.eevblog.com/forum/projects/buck-loop-stability-tuning/msg5453216/?topicseen#msg5453216 As with any spreadsheet per B. Pease (For reference, see his columns https://archive.org/details/Bob_Pease_Lab_Notes), you can only trust it if, and only if, it doesn't have any mistakes in the formulas it's built with...
Tips/Techniques
Stock 5V and 12V
These are the most common voltages. Always try to standardize on the most common barrel plug (which is I think 2.5mm, and 5.5mm or thereabouts).
Diodes Gone Wild
He has a number of videos that diagnose broken switching power supplies and is reasonably knowledgeable about them.
Example of 5V 8-pin DIP Regulator
https://www.eevblog.com/forum/repair/need-help-to-identify-a-blown-chip-in-skynet-for-z12c-switching-power-supply/msg5445107/ It's always easy to spot the capacitor and diode.
