 Stanley Kubrick (qv) worked for several months with effects  technicians to come up with a convincing effect for the floating pen  in the shuttle sequence. After trying many different techniques,  without success, Kubrick decided to simply use a pen that was taped  to a sheet of glass and suspended in front of the camera. In fact,  the shuttle attendant can be seen to "pull" the pen off the glass  when she takes hold of it.