I think that you have made a decent start. Your sketch looks like it was relatively fast nor was it overdone.
There is a certain amount of detail that is need for the basic function of the drill. You need comfortable handle sections, intake, exhaust, space for a trigger box, and allowances for internal components. Look into all the basic components that make up a powered drill.
I think that you have not done enough research. Do a search on the internet for the various drills out there, and the components that go into them.
Your design looks it could pass for an entry level screw-driver, but the handle section looks too thick. It is good that you are using foam. That will quickly show you what a comfortable section feels like. Remember in tools, the feel is more important than the looks- and the feel has to be good even after a few hours of holding the tool.
Sometimes, you can afford to be simple. If you propose this to be a low speed, occasional use driver, then perhaps you can get away with minimal venting, but you need to make allowances for air-flow. Most times though it is a struggle to keep a tool simple.
Look on wikipedia, and other sites for information on drill components. There are plenty of drill reviews online, that state what is important to look for. Purchase a cheap drill and strip it down. Look for inefficiencies, and ways that you can change the internals so that you can make an ergonomic external design. Look online for parts suppliers, that have different options. Design some of those internals yourself- you are a student- this is a way you can show out of the box thinking.
An entry level driver is a good student project, but to take it to the next level, you need to consider the internals. This is what real- world designers struggle with everyday. Consider new technologies. If you still want this to be a styling exercise, then at least use the internals from the cheap driver and design around it, making sure that you have similar functionality built in.