Building with two parts touching?

What properties i need to change so the Parts can entry in each other. Just like that.

         ---------------
         l                l
         l                l
         l                l
         l                l
         l                l
         l                l
         l                l
         l   -----------l
         l  /             /
         l/              /l
        / -----------/--
      /               /
    /                /
  /                 /
/                 /

/ / / /

Idk how to express myself so i made a illustration. One part is entering another but the player can still walk in them. wanted to use this to make curves, etc. Its not Anchor or CanCollide so idk

Go on Model on the top of the studio and turn collisions off.