This is a Parametric Gridfinity model made using Fusion 360. Download the file, open with Fusion 360, and then change the size of the grid and spacers as needed. 

To change the parameters, click on “Modify” then click on “Change Parameters.” From there you can change the size of the grids (Rows and Columns). You can add or delete any spacer, and change the width up to 21mm. To remove a spacer, set the size to 0mm. 

Example:

 Let's say you have a drawer that's 134mm wide. You can fit 3 full grids in that space: 3x42mm = 126mm, which means there will be an 8mm gap. Divide that 8 by 2 (for the two side spacers) and you get 4.  So if you make each side spacer 4mm, the grid will fit perfectly with no sliding around.  You may want to leave a little room for error, so make the side spacers 3mm each instead.