Turn the cabinets upside down and screw the CAPITA legs into place. After that, you can stand them up again.
You can also connect the individual cabinets together with screws. Screw in through the dowel holes from one cabinet to another. Make sure to get screws that are not too long, in order not the puncture through to the inside of the adjoining cabinet.
Fix the drawer into the wider cabinet to create the bridge.
Now that you’ve got the structure done, place the 80cm UTRUSTA shelves in the cavity of the fireplace. These are to hide the dowel holes on the sides.
Place the shelves upright, against the left and right sides of the cabinet. If you want, you can fix them with double sided tape or similar.
For the mantel top, I placed a wooden board I bought from Amazon.com, which I got rather cheaply. You could also use the IKEA cover panels or countertops for this purpose.
Decorate it up
Lastly, the back of the fireplace.
With SÄVEDAL doors and fronts
You can design the back wall of the fireplace any way you wish. I mostly used a thin chipboard and papered it with a 3D peel and stick brick or stone pattern. You can be completely creative and design it to fit your home decor.