Hi @MartinCol in Easel you can use the exact dimensions in the "shape" tab of the floating tool bar. You can also design a file in another program and export it and import it as an SVG.
We are working on a way to import other file formats and we will announce that later this year. Until then those are your only two options with Easel.
You can also use any other CAD/CAM program and send gcode to the machine using a free sender like Universal G Code Sender or Chilipeppr.