How do you make your own cubemaps?

Is anyone making custom cubemaps for rooms?
I am guessing everyone is using Vray, could you pass a long any tips you have on the work flow,
We are using Corona and the scale is way off despite all the “scale” suggestions, seems it’s a Corona work flow thing,

We use Corona spherical camera for VR and pass it through cmft studio to get he cubemap faces that work directly with Play Canvas, so guessing there must be an easier way to do this with Vray
Any hint appreciated!