We originally built the original console a while ago as an entertainment unit for underneath our television. We enjoyed the console so much that we decided that we wanted to do another modified console with a fireplace in it and make the other one into a buffet/storage area for the dining room.
Both of these are fairly modified from the plan, however the basic concepts remain the same. One big thing that we did was use 1x4s as much as possible to reduce the different sizes of lumber we were buying to both reduce complexity and end up with as little as possible scraps.
The frames are made of the 2x3s, The sides (4 deep), shelves, middle shelves and face frame are all 1x4s. The back and inside frames are scrap plywood. The top is 1x6s.
The addition of the fireplace was not difficult. What it did require us to do was to add the centre section and essentially create a box that is closed to the outside cabinets. If it were not closed off it wouldn't support the fireplace insert correctly. The important piece with the fireplace is to ensure you have enough clearance on the top and sides to allow the fireplace to mount safely without overheating. The nice thing about this setup is the additional shelf above the fireplace which we used for electronics. The wires go through the back of the cabinet and it looks very clean.
These are probably my favorite things I've built this year. They're simple to make and add a lot to any living space.