Can anyone help me with the best way to go about creating a design for a holder for small pliers?

Most of the small tool sets I have came in either a case with molded sections to put the different tools in, but the pliers did not.

I tried laying them out on white paper and taking a photograph and then converting that to black and white and filtering it until just the outlines were visible, but this did not work well for me. After sending the final image to shapeways to get an stl, I was never able to get the dimensions perfect to where the tools would fit in the "cutouts".

Thank You!