Photoshopping - Edge finding

[arseofbox]

Im currently trying to convert this picture of an inlet gasket into a CAD model...so I can build up a model of my full intake system.

I scanned it in in two parts and stitched it together as one file at 1:1 scale.

I want to pick out the edges and lines from the image - basically finding the edges and the holes if this makes sense - as Im gonna convert the colour depth to 1-bit so I can pull the dimensions off from a line art picture in the CAD package.

Ive erased the logos printed on the gasket face, although not very well...does anyone know how I can pick the edges out? I want a picture like the first attachment, startuing from the second. (although the attachment is 16.7m colours).

Ta

 

[arc]

photoshop magnetic lasso tool?

 

[serin]

photoshop magnetic lasso tool?

thats not very precise

Id prefer to zoom right in an use the polygonal lasso to do it myself

 

[pranksta]

Dont know wheteher your familiar with the toons done on photoshop but it could be done this way as with them you follow the outline of a car or something like that and turn it into a pic like your 1st attachment.