Vertex-H with Double rail along X-axis

Soon after completing build of Vertex-H published here I discovered that, due to poor quality of inexpensive linear rails, the tip of the nozzle freely moves along Y-axis. The play was about 0.4mm and my solution to get rid of it is published here. I have to admit – this was quick fix; I tried to keep as many existing parts as possible. Clamp add-ons are mounted with M3 screws. Initially I tried to mount them with 25mm screws but then ended up using M3x50mm screws that went all the way through old clamp and the add-on. M3 self-locking nuts keep this clamp "sandwich" together. Newly added X-rail length is the same as the original - 300mm. All cheap rails are different; if the screw holes in the clams are not aligned with the holes in the rail, you may need to tweak the clamp shape. Assembly is a bit tricky. Place new rail inside the opening in carriage-top piece and move it towards the front of the printer. Keep sliding block outside carriage-top piece. This will give you access to 2 holes attaching carriage-top to the back piece. Put socket cup head screws into the holes through the side openings and tighten through the top holes with Allen wrench. Once parts are tightened together, slide the block into its place in carriage-top piece and attach to carriage-top with 4 M3x6mm screws. I uploaded carriage-top thing for both – custom and the original PCB.