Test them submerged in a fluid with (approximately) the same density and the material they're made of and they are "weightless" for all intents and purposes. Th

Test them submerged in a fluid with (approximately) the same density and the material they're made of and they are "weightless" for all intents and purposes. The fluid will add some other dynamics which are not present in a vacuum so the test will not be entirely accurate but it will show whether the mechanism does what it is supposed to, mostly.