building a partial passthru

I would like to build a feature that would let you use your vr headset in "partial" pass thru. In other words, I would like the option to be able to see my real feet and a little of the surrounding area when in vr. The app Fluid has this feature where you can toggle pass thru, vr or a partial pass thru and see your feet. It is similar to some that let you see your real keyboard in vr. Anyone have any thoughts of this?