If you want to build something on a Mauser, Remington, Winchester or Ruger action you're going to need a lathe and some machining knowledge... You can purchase Pre threaded, short chambered and crowned barrels but you still have to face the chamber end and shoulder. You also have to assemble and then hand ream to fit go and no-go gauges for proper headspacing. Going to need some sort of action wrench and barrel vise to hold it all and put it together / take it apart. If you want to get into truing the action and or machining a barrel blank it gets all that more complicated in the machining department.

You can go from as simple as a Savage 110 and screwing on a new barrel to buying an in the white receiver and customizing until your heart is content. Entirely up to you.