Some of you wondered where i made those lego things in.
There is this wonderful free program called, Lego Digital Designer which allows you to do just this.
I am aware other programs exist, so maybe google your options. I originally started using LDD simply because it allowed you to do a part inventorisation ,generateS a build guide; but in its glorious past it actually enabled you to order the things you built in it, which ofcourse, is an attractive idea. But that got removed in subsequent updates. So yeah.