It took: fan on the foot (delicately disassembled, I will assemble it back in summer), a chrome-plated 25 mm thick-walled pipe from advertising equipment, 2 adapters for such a pipe, two MDF panels about 40 * 60 cm in size - one as a support under the bed, the second as a table.
I made a negative tilt in advance by placing thick washers, because I realized that the design was flimsy, and bent under the weight of the laptop.
With the table everything is clear, that was at hand, then used.
Initially, I wanted to make this design on wheels, like what I saw in the hospital, but my bed was low, the wheels could not fit in there, but the platform board comes in tight and provides stability. On the laminate floor, it easily enters and exits. I wanted to saw off the bar, and then I thought that I would not spoil it, well, big and big, in which case you can hang a dropper.
The first adapter (top) is slightly twisted so that the table spins. The 2nd adapter (lower) is a height adjuster and is tightly twisted.
The key is a 6-sided key to it then, possibly, I will replace it with a lamb.
It was still necessary to insert a steel bracket at the back, since with awkward movements the laptop cover strives to lean back.
And most likely I will replace the bed with a large 12 mm laminate board, it glides too easily on the laminate floor