My object is wrong :-(

My object is very different to what i want. I'm sure i made a mistaken somewhere but i don't know what .
Every circular line in my object became polygonal (not only what the red arrow points) and also where there would be some empty slots for my coins there are slots full of plastic.
This is what i made:
I draw my project with autocad 2008.
Then i opened it with 3ds Max 2010 Trial version.
I exported it with .dae extension and finally i loaded it in the shapeways database.

So what was wrong?

Nobody can help me?

Did it look ok in Max?

I would say yes but... it's not true.
Here is the problem. When 3ds Max import the dwg something go wrong.
So how can i convert my dwg?

And the second problem? why my slots are full and not empty for my coins?

Your issue is the conversion from CAD to Max. The way that AutoCAD does things is different from that of Max, so objects will not always look the same, such as the smooth edges and holes. Unfortunately, I don't know any fixes other than remaking it in Max, but I'd ask around 3d communities, because I don't know much about either program. Wish I could help more

it's been ages since I used autocad, but I think you should check your surftab1 and surftab2 which defines how many segments autocad uses to draw curves

you might have to redraw those sections of the model tho, I don't think surftab settings affect entites already drawn, but I could be wrong.

Thank you everybody for the help.
I don't know anything about "surftab" so i don't know if it is the problem, but i don't think it's an autocad problem. In the dwg file the object is perfect. you can see it in the first image. I made the second only to show the difference from the first.

Whilst you are superficially right (there is nothing wrong with the Autocad model) it is the conversion process that is causing your problem. Autocad uses mathematically defined curves to draw circles and similar (i.e. your model) but Shapeways uses polygons in all the formats it accepts (and it takes a lot of polygons to accurately represent a large curve to within a small degree of error.)
When you attempt to convert formats, the software looks at your model, says "This is perfectly nice curves, but I must turn them into polygons, or it won't work." So it does - but it doesn't know how many polygons exactly you want for each curve, or anything like that. Instead it takes a rough guess, and the result is your model gets messed up as shown above.
Two general solutions may or may not apply, depending on what you want.

1) Change the model inside Autocad, either so that it assumes more polygons for each curve when converted, or by converting the curves to polygons yourself.

2) Or, export the model and then manually correct the curves by subdividing and smoothing them using some other software, so as to achieve a decent approximation of the original curves.

Neither of these is particularly handy, but at least one of them should work.

I don't know much about Autocad, but I'm very familiar with 3D Studio Max. It looks like you're model is defined by Splines, instead of straight up Polygons. If you go into the Edit tab and "Convert to Mesh", you'll see what your model truly looks like.

I'm willing to bet there's a conversion tab somewhere that allows you to define how many polygons are created for each and every arc you have. You just need to turn up the number until it's smooth enough to fit your needs. For instance, instead of 1 or 2 per 90 degree arc, you probably want more like 32 to 48.

In AutoCAD, you need to type FACETRES at the command line. The default value is 0.5. Set it to 5 or higher. This will smooth your curves, including existing ones.

I'd not bother with 3dMax ... just export direct from AutoCAD:
Drop the file menu, choose "export", drop the filetypes list, choose "lithography(*.stl)".

The .STL file is directly usable by Shapeways.

Thank You very very much