Study "Assembly.skp" or "Assembly.stl".
Print all pieces as shown in "Assembly.skp" or "Assembly.stl". I added hold down disks to "Base.stl" to assist in minimizing warping, carefully remove them after printing.
Test fit and trim, file, sand, etc. all parts as necessary for smooth movement of moving surfaces, and tight fit for non moving surfaces. Depending on the colors you chose and your printer settings, more or less trimming, filing and/or sanding will be required. The return track, especially where it enters the landing area, will need to be carefully trimmed, filed, sanded, etc. in order to remove the striation artifacts of .2mm 3D printing.
Assemble as shown in "Assembly.skp" or "Assembly.stl".
Feel free to comment if you have questions.
Hope you like it!