Final answer:
Innovation in 3-D printing and increased optimism in the economy will likely cause an increase in output, employment, and potentially stabilize or moderately increase the price-level due to enhanced productivity and reduced production costs, along with increased investment and consumption.
Step-by-step explanation:
When firms are more optimistic about the future of the economy, they are likely to increase investment and production in anticipation of higher future demand. This optimism, combined with innovation in 3-D printing technology that enhances worker productivity, leads to an increase in the economy's output.
The rise in productivity means that more goods can be produced with the same amount of input, which reduces the cost of production. Consequently, this can be represented as a rightward, or downward, shift in the supply curve.
With increased output and lower production costs, firms are able to hire more employees, leading to an increase in employment.
Additionally, the improved efficiency may prevent prices from rising too quickly, potentially creating a stabilizing effect on the price-level. However, if the demand increases substantially due to higher optimism, prices may still rise if demand outpaces supply.
Overall, these factors combined are likely to result in a boost to economic growth, given that both supply and demand are positively affected—supply through increased productivity and lower costs, and demand through heightened economic optimism and the subsequent increase in consumption and investment.