RE: 3D Printing - IN SPACE!

My understanding is that because layers are being applied the first layer sticks to the print bed and the nozzle is close enough to each layer as it is being applied so the extruded material fuses onto the prior layer before it has enough time to float away.

This video showing jelly being spread to make a sandwich on the ISS seems to demonstrate an analog of that. A material spread on a surface that is weakly sticky is enough to maintain the material in place.