I have been toying around with making a custom bass from parts (like from Carvin or Warmoth). I am a reasonably handy guy. I have an ample workshop with most of the necessary power tools. I can solder my way out of a paper bag. How hard is it do do all the stuff yourself? I would leave fine tuning the setup (nut filing, bridge adjusing and truss rod adustment) to a professional. What is the hardest part?