The best replacement for caster is camber.

The best alternatives to caster are rated as following:
★★★★★  camber
★★★★  castor
★★★  granulated sugar
★★  icing sugar
★  commentator
★  pinion angle
★  melee wow
★  spin caster
★  wheel
  chester
  less caster
  bait caster
  spinner
  melee skyrim
  negative caster
  white sugar
  soft caster
  caster

Your alternative for caster is not listed? Suggest!
Speaking about caster, one probably shouldn't forget about leveling foot.

Other search terms related to caster and their ratings are:
★★★★★ leveling foot
★★★ 1/2 threaded stem
★ floor lock
You have in mind a companion for caster and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of caster in all years. Click on graph for more.
caster
camber
castor