Hi,
well the handle looks good!
I ran the model through Netfabb Basic (which is free) and made a simple repair, which fixed some issues but not all.
The problems I have seen:
1. There are some stray vertices. There are some in the middle of the object which look like they should not be there, and at least one on an end face;
2. The meshes you have created are not watertight and non-manifold. To make a mesh to print each part must be a watertight mesh and the different meshes must overlap, they cannot just touch. Non-manifold means that a Vertex, an Edge or a Face of one mesh exactly coincides with one of these attributes of another mesh;
3. I'm guessing that your model was constructed in SketchUp, which unfortunately I know nothing about, but there are some very knowledgeable (and helpful) guys on the forums JACANT and Denali3ddesign among others. If you search out their posts on this subject I am sure you will find it helpful. The problem essentially seems to be that you have 'tiled' together elements without actually joining them.
I hope this helps a little bit,
good luck