The biggest current risk is still the mechanical design as it has many uncertainties and because the software components have been mostly fleshed out already. To mitigate this risk we have gone ahead and ordered the platform jack we plan on using. We will begin testing next Monday. Depending on the friction of the linkages in the jack, we will determine how much torque we need in our stepper motor.
In case the platform jack fails for whatever reason (too much torque required or its top platform is not level), we will purchase a more expensive jack that is manufactured better but is also heavier.
One minor change to the design is that we are now planning on using bluetooth communication between the computer and the arduino since this is simpler than we thought and will contribute to our use case requirement of our product having a smooth and simple user interface. There were no real costs associated with this change since getting the bluetooth code written was minimal work.