Since the base is over five-feet long I decided to use a torsion box to prevent it from sagging. The weight of the router is directly on the ends over the wheels so I also made the sides torsion boxes.
The entire cabinet is made from 1/2" birch plywood. I had originally intended to build it with a cheaper grade of ply but found that the 1/2"-B/C ply at Home Depot was as crooked as a barrel of snakes. The 5/8" was a little better but heavier and more expensive. It was only a few dollars more to go to the birch from there so I jumped. After getting the ply home and unloading it I found the "Made in China" sticker.
I followed the same procedure for this torsion assembly as I did when building the router table.
The ribs in the base are three-inches tall. I added some corner ribs to stiffen the box where the wheels attach.
I didn't put cross braces in the uprights since they are not very tall. I left the outer skin long to cover the end of the base. The ribs in the sides are 2-1/2" wide.
Even before the dividers were installed the whole thing was incredibly rigid. I changed from the original drawing and only put two openings for drawers. I think three would have made the drawers too narrow. Also, fewer drawers will reduce the cost for the full extension guides.
The next challenge was getting the 200+ pound machine onto the cabinet by myself. I knew I couldn't pick up the machine so it would have to be dragged into place. Since the cabinet is the same length as the router it would be difficult to move one end then the other without the risk of it sliding off the end. I gave this one a good deal of thought and finally came up with a plan that showed promise.
I locked the wheels and ran an eight-foot 2x4 under each side of the cabinet until it hit the back wall of the shop. The machine was sitting on two sawhorses which in turn were on a piece of plywood with wheels. Since this was taller than the cabinet, I clamped some boards on each end to act as a track. On top of those I used two piece of UHMW plastic to make things slide easier. After that I just alternated back and forth between the two straps until I had it in place.
I used birch edge banding to cover the plywood edges where they will show since I had a roll on hand. The styles and rails are also 1/2" ply with edge banding. Two coats of exterior polyurethane make up the finish.