How to build an adjustable creeper?

Due to my knee replacement and being older in general, I find it very difficult to work under anything including a car. I can lower myself down on the normal creeper. I have a model railroad and need to get under it for maintenance, repairs, and building new features. Below are two examples of the kind of thing I need and want to build. I would hope maybe someone on here has done this or has some ideas.

https://www.youtube.com/watch?v=ATxz0y7JVa8

https://www.youtube.com/watch?v=OCdT...ature=youtu.be

The first one is the best example of a creeper that would help my situation. I do have metal and wood working skills and tools.
Any ideas would be appreciated.
Jay Beckham

Moving this one into our Tools in Progress subforum so you can get some good ideas.

BTW we recently featured the Human Hoist chair. Similar concept, although I don't know if it's for sale yet, and if it is, it is most likely quite expensive. GIF below, and more details here: https://www.homemadetools.net/forum/...8169#post86925

https://s3-us-west-1.amazonaws.com/h...rage_chair.gif

Look at a scissor jack from a front wheel drive vehicle, then scale it up with a mobile base plate similar to a mechanics creeper. You may even be able to use a creeper and just install a modified electric scissor jack. You would only need about 20 inches of lift.

Here are some product links for reference.
https://www.amazon.com/Black-Bull-EJ...75911231e7e62b

https://www.amazon.com/USA-Made-Prof...f00053f7a4fbb8

https://www.amazon.com/Traxion-1-100...fd0d4a28ab3f65

https://www.amazon.com/Torin-TR6452-...a7e23c2dc1e95b

I would use a fast acting linear actuator 12v DC and run it off of a 18v Milwaukee battery

Look for a used "Hospital" type bed (try Craig's list). should provide the actuators and hinges as well as control & scrap steel.

Hi Jay,
May be you could adapt this.
http://ricksfreeautorepairadvice.com...anics-creeper/