Tinkercad Easy Fillets (rounded edges)

I whipped up a javascript Smart Shape which makes creating straight edge fillets quick and simple. Drag the fillet to your canvase, adjust the size, change the color to hole and group with your object.

This thing was made with Tinkercad. Edit it online (Don't use the download button) https://tinkercad.com/things/la63cSw4tbV