Dial Indicator Backplate

I purchased a cheap dial indicator from Amazon to use for bed leveling. It came with a flat back plate although the product pictures showed otherwise. Rather than go through the hassle of return and reorder, I decided to design my first part. I don't own a CAD program so I used Cinema 4D.

Vktech Dial Indicator Gauge
https://www.amazon.com/gp/product/B00MUCQ4EM