Belo (2010) uses a production function
$$
Y_{j,t} = \epsilon_{j,t} F^j(K_{j,t})
$$
where a competitive producer $j$ is allowed to choose the state-contingent productivity level $\epsilon_{j,t}$, subject to the constraint set
defined by the following analytically tractable CES aggregator:
$$
E_t\left[ \left( \frac{\epsilon_{j,t+1}}{\Theta_{j, t+1}}\right)^\alpha \right]^{1/\alpha} \leq 1.
$$
In Cochrane's 2016 essay, "Macro-Finance", Cochrane mentions this specification as a potentially important ingredient for understanding the interaction of macroeconomics and financial markets:
The second ingredient, I think, is to enrich the production technology
so that consumer investors can shape the riskiness of the
technological opportunities they face. Belo (2010) and Jermann (2013)
have recently explored specifications of technology that allow such
choices.