There are essentially 2 schools of thought on TT design. Low mass-high rigidity, and high mass. High mass is probably easier for a DIY'er to handle since there's little additional "tuning" that is required for a low mass design, and therefore is less trial and error prone.
Designing a TT is mostly about resonance control and tight tolerances on some key parts. After that it is about speed stability. I would stongly suggest keeping things as simple as possible to avoid pitfalls that you may not be able to anticipate in your first attempt, such as using a manufactured arm rather than a DIY (unless it is an exceedingly simple design).
Good luck whichever way you go and remember there is more than one way to skin a cat as the variables add up pretty quickly.
Designing a TT is mostly about resonance control and tight tolerances on some key parts. After that it is about speed stability. I would stongly suggest keeping things as simple as possible to avoid pitfalls that you may not be able to anticipate in your first attempt, such as using a manufactured arm rather than a DIY (unless it is an exceedingly simple design).
Good luck whichever way you go and remember there is more than one way to skin a cat as the variables add up pretty quickly.