How to Make a Floating Platform

one way is to use constraints with force limit. if you use constraint entity, negative limit values specify that when the limit is reached it won't break, but just won't apply any more force. in constraint flowgraph node (and, of course, in c++ code) this flag is explicit. note that it's not a spring in the strict sense, i.e. the force is not k*offset, and if the object's mass*gravity is more than the constraint limit, the platform will just keep dropping and the constraint won't be able to stop it. it's generally a more stable solution, but it may or may not be what you want. you can also add any custom impulses yourself by subscribing to immediate poststep events from the platform rigidbody (set pef_monitor_poststep flag and add a listener with AddEventClient)