Its vision is ambitious, but can it actually be made to work? In the last three months, Ginkgo Bioworks' (DNA -10.27%) shares fell by 50%. To the enterprising investor, such a decline by the Boston-based biotech specialist isn't necessarily a sign of disaster, and in fact could well be a sign of an opportunity to buy shares at a discount -- assuming those shares can be reasonably expected to rise again in the future. Is that the case with this company, or would it be better to look for opportunities elsewhe ...