Great job Bob;
You asked about any suggestions.
Put a bycicle pedal type handle on it to make it easier for you to turn it.
Since the opening is where it is, try putting doors on the sides to make it easier to push the composit out the main door.
When looking for paint, get the paint that adheres to plastic.
The paint designed for metal or wood will just keep chipping or peeling off.
Hope this gives you more ideas.