Print the top, it's all you need for it to work. I printed the working model with 3 shells and 60% infill and I don't have any leak issues.
Print the bottom, to catch draining fluid and so you don't make a mess. with the same 3 shells and 60% infill.
- HAVE FUN WITH SCIENCE!!!
Update: Uploaded fixed files that were ran through netfab. You may have better results with these files.