Create your working space... this is the outer dimensions of your Jig.

You might need to adiust this once you have your item outlines placed.

Create your item outlines and make sure they are sized correctly.

Place your item inside your working space.

If you want more than one item in your jig, copy and paste and arrange them accordingly.

Then you cut out your item outlines. Then you cut out your working space.

Same basic concept for XCS.