High Current Power Supply Design
We will keep this easy and simple. Use buck converters to create your low voltage. You can buy them easily if you are in a hurry. Keep the outputs close to your loads so you do not have to worry about voltage drop along a cable. The buck converters that you buy might be happy on say 12V input which is common in computers. You can just buy a PC power supply to get the 12V if you are in a hurry.

If you do decide to use a transformer, bridge rectifier, and filter cap it will now be easy because the voltage does not need to be exactly 12 and the buck converters will happily attenuate any ripple from your rectified filtered DC. In other words the filter cap does not have to be too huge. If you don't buck down you will need an oddball transformer with enormous filter caps and big diodes only to get rewarded with poor voltage regulation under line and load changes.