Hi again. After a I while now i am going to put my free time into designing as much as possible. For now i have just several main extrusions with rails and blocks on them. Now want to start to count what exact lenght I need of extrusions, where to place rails and ballscrews, which is quite confusing to start with. I am considering if it is worth to buy custom made rails and ballscrews lenght to my exact dimensions, or it is cheaper to have a bit smaller work area than I wrote in my first post and to go with standard lenght which is 1500mm and 1000mm? I mean how expensive it can be to have those lenghts of rails and ballscrews at those dimensions, which could let me have exact 1500x1000 work area.

Here is the picture how it looks at the moment.
Click image for larger version.  Name: Base frame.jpg  Views: 893  Size: 114.7 KB  ID: 17508

All the corners i am going to join with 90 degree L shape brackets. Do i Need the legs? If yes, then probably it would be nice idea to have a pair of legs in the middle yes?
Thanks a lot! :)