Update 12/8/2016: Added an image of the part dimensioned the variables described for further clarification.

I needed to make a nut trap that would fit with my customized tool holder I am designing to fit a Mastergrip rotary tool I bought at Costco years ago, so I decided to make this part parametric.

Spacing for my tool holder is 53mm distance between holes.

I made a parametric drill jig that will help you drill holes to use with this nut trap. Here is the link to that part: http://www.thingiverse.com/thing:910707

Here is the link to the mastergrip rotary tool holder I made using this size nut trap: http://www.thingiverse.com/thing:909366

You can also open this with Thingiverse Customizer.
Here are the links I used to show me how to get this to work in the customizer.

Here are the links I used for help in making this work in the makerbot customizer.
http://www.makerbot.com/blog/2013/01/23/openscad-design-tips-how-to-make-a-customizable-thing

http://www.makerbot.com/blog/2013/01/18/design-unique-things-easily-with-makerbot-customizer

Here is the link to the openscad template mentioned in the 1st instructable for making your openscad files work with the customizer
http://www.thingiverse.com/thing:44090

Open this with the Customizer or edit any of the variables in the openscad file to adjust it to your liking. The NutSpacing variable is main variable to change, but there are 11 other vaiables you can change. I included the 53mm spacing file I used for the tool holder I am using.