Picture of Vibrating bassinet to calm baby
We had a new baby, a vibrating bouncy seat and a play yard with the bassinet that she was to sleep in.  But while the bouncy seat had soothing vibrations, it wasn't safe for the night, while the bassinet which was safe for the night had no soothing vibrations.  
A bit of work, and we have a vibrating bassinet, thanks to a very easy hack to the vibration unit from the bouncy seat which can now easily travel between the bassinet and the seat.

While one can buy a vibration unit for a crib, the Amazon reviews of it are mixed, and it's not designed for a bassinet.  And there are vibrating bassinets but they are way more expensive, plus the one we bought didn't have that feature.

WARNING:  USE AT YOUR OWN RISK.  Do not leave the vibration on while baby is unattended or you're asleep.  You don't want the motor to overheat and cause a fire.  (In our bassinet, the vibration unit rests on netting, so heat dissipation should be not much worse than in the bouncy seat, and I haven't felt it get warm.  But better be safe.)  CONSULT WITH PEDIATRICIAN IN CASE OF HEALTH CONCERNS.

This works for our new play yard and our old model of bouncy seat.  You will probably have to modify the hack a little for other models.  It may be that on some models you will be unable to easily move the vibration unit back and forth.  If so, then you might see if you can buy a cheap old bouncy seat on Craigslist to cannibalize for the vibration unit.

  • Baby Trent Nursery Center Playyard with full-length bassinet
  • Linkadoos Bouncy Seat. The current Fisher Price bouncy seats look like they have similar vibration units from the Amazon photos, but I can't tell how they are attached.
  • Scrap Velcro or other hook-and-loop fastener
  • Something foamy to cushion vibrations, like a mouse pad or foam drink holder (that's what we used)
  • Adhesive for attaching hook-and-loop fastener to vibration unit
  • Screwdriver