Sigma 20 x 20 profile compatible toolbox

For a very long time I use 3D software for industrial visualization.
Now I am 3D printing for my own DIY projects and as a beginner, I wanted to create something basic, useful and extendable.

As sigma aluminum profiles are common for most of 3D computers, I prefer using this profiles as an adapter for my designs.

I use 3DS Max for creating a dummy aluminum profile at first.
Then I created a sigma compatible slider.
Then attached a small box at the end of that slider.

I hope you guys enjoy this project as a beginner, how to design something new from scratch.