that is a good idea nofsky, i am trying that right now and it is the closest i found to what i am trying to achieve, thanks!
edit : i found a semi-solution, i play with gravity, impulses and block boxes that are blocking everything but the player. But i still have problems making a good loop with impusles, i try something like :
while (1)
     {
          AddTimer("", 1.0f, "LevitateUp");
          AddTimer("", 2.0f, "LevitateDown");
     }
void LevitateUp(string &in asTimer)
     {
          AddPropImpulse("MyChair", 0.0, 1, 0.0, "world");
     }
void LevitateDown(string &in asTimer)
     {
          AddPropImpulse("MyChair", 0.0, -1, 0.0, "world");
     }
I know my while loop is an infinite loop, and it is making the game crash, but i think maybe i don't know where to place it. I want the levitating effect to start as soon as the player enters the level. Any input? Thanks.