Lightly sand the surfaces of the desk you want to paint and wipe off the dust.
Then, paint the parts you want in grey. You may need to do two coats. (IKEA also sells the HEMNES desk in a grey and black brown version, if you rather not paint)
Let it dry.
Then, wrap the table top with marble vinyl sticker. Be careful to wrap the corners nicely.
Secondly, the add-on unit.
If you wish, paint the small drawers and stick grey fabric onto the backer board, for a more uniformed look.
We omitted the slanted shelf for documents on the left section and the removable shelf in the middle and right section, as they weren’t useful for this purpose. But if they work for you, by all means, use them.
Next, measure the cavity of the add-on unit and get a mirror cut to size. Mount the mirror on to the backer board with strong mounting tape. We placed it resting on the raised edge, which helps take some of the weight.