Ender 3 Z-Axis Support

Just print it in the orientation it comes, unbolt the top rail press it onto the end (you may need to hammer it lightly), then lower it back on over the rod and put the bolts back in. 

There is also a skeletonised option just because why not? It uses slightly less filament but takes longer to print. It's probably no weaker, so if you want it a bit fancy use the “Skel” one.