As folks get to a certain age - particularly those with physical issues - may find getting in and out of bed a bit of a challenge. My wife's Parkinson's is one example of that.
Per recommendation by her physical therapist I ordered the much highly rated commercially available contraption. I returned it once I put it together because I didn't believe in its stability, let alone the complicated way of its installation, particularly on a king size bed.
So, I came up with my own version as a woodworking project. One significant difference is in the two support legs. I designed mine with feet - a prominent heel and extended feet, which adds to the stability. The horizontal platform - the tongue - inserts in between the bottom of the top mattress and the top base of the bed frame.
It is stable enough but a nut and bolt (see next photo) secures it to the bed frame. The apparatus can be conveniently moved away when the need to change the bed sheets arises.
A friend had given me a while back some leftover wood flooring pieces -solid oak pieces with one side finished.
Tapering the feet (below).
I created the notches on the legs to which matching notches on the feet will allow for a strong joint (using screws only)
Drilling the pocket hoes for pocket screws
Below - shaping the heel of the feet
The grab bar is commercially available. I've used several in each of the bathrooms for my wife's use mainly.