A Calculator, a White-Board and hand-made design. Is it possible? Is is reliable? I'm curious.

HI! I'm curious about some legendary Event-Driven Hedge Funds. Like, Farallon Capital. Is there only hand-design for price modeling, at some firms? How is it, actually? I like to design, I'm just curious, because I like it too much, and I simply love the idea of modeling prices, calculating and making investment in a reliable way. Do you have any experiences doing this at a firm? Have you seen it? I like computers, but I love simplicity. I think that a company should have both. What do you think about it?