If you are into pneumatics, you can choose to have your lid open and close by means of a 12in pneumatic cylinder mounted to the foot of the coffin. See the photos below.

In order to have the cylinder hidden I chose to build a housing over the cylinder that would not only hide the cylinder but allow me to hide plugs or anything else I decided to add to the coffin's interior. I also added a pin switch that allowed my internal lights to only turn on when the lid was opened, therefore avoiding the risk of fire. That light gets really hot in a sealed and padded enclosure, so if you don't install a pin switch, I don't recommend adding a light inside.

Regardless if you have a light or not please be careful. Most fabric will easily catch fire, if a lightbulb is near or touching it you have a potential fire hazard. I'm sure after spending a few hundred dollars and countless hours on this project, you wouldn't want to see it go up in flames. (Also the fire marshall won't approve it if he/she sees it.)

The easiest way I found to pad the inside was to first cut the fabric so its about 8 inches bigger(4in on each edge) then the area you are working on. Then staple the fabric to the edge with the fabric laying over the sides of the coffin(covering the handles).

Now add your poly-fil to the inside of the wood and cover it with the flap of fabric and staple it to the bottom wall of the coffins interior. Do this to each side, bottom and lid of the coffin and once your happy with the way it looks, add your upholstery tacks. This is a must to get that thick padded look.

Re-attach the lid and you're done.