We will require concept art for the tesla generator. The tesla generator is a human base defense structure that zaps incoming aliens with automatically targeted bolts of electricity. It is invariably fatal to smaller alien forms, while larger aliens can usually ignore it long enough to destroy the generator. Regardless, it is very effective when used in groups, or in conjunction with the machinegun turret.
In Tremulous, the tesla generator looked like this:
You can deviate from this design as far as you wish. In fact, it's encouraged. The sole constants are that the tesla generator must be roughly as tall as a human, relatively narrow, and capable of damaging nearby aliens quickly. You don't even need to stick with the electric effect, as long as you can figure out something that fulfills a similar function.