https://circuitdigest.com/article/how-to-make-a-pcb-at-home

Biofeedback is the process of gaining greater awareness of many physiological functions primarily using instruments that provide information on the activity of those same systems, with a goal of being able to manipulate them at will. Some of the processes that can be controlled includebrainwaves, muscle tone, skin conductance,heart rate and pain perception.

Biofeedback may be used to improve health, performance, and the physiological changes that often occur in conjunction with changes to thoughts, emotions, and behavior. Eventually, these changes may be maintained without the use of extra equipment, for no equipment is necessarily required to practice biofeedback.

Biofeedback has been found to be effective for the treatment of headaches and migraines.

https://en.m.wikipedia.org/wiki/Biofeedback

https://www.medgadget.com/2016/01/medgadget-ces-2016-omron-project-zero-wearable-blood-pressure-cuff.html

Source: ZoneMinder Wiki – Wiki – Ubuntu Server 14.04 64-bit with Zoneminder 1.28.0 the easy way

There are many ways to make your own homemade PCB’s, They all work, but some better than other, some faster than other, ones are cheap and others expensive….After several attempts, i found the way of making PCB’s, wich is the cheapest, easiest and fastest for me.I hope this instructable will help you to decide what’s the best method for you, because there are so many to choose.

Source: PCB Making Guide: 8 Steps (with Pictures)

JYE Tech offers DIY handheld for hobbyists.

Source: JYE Tech: DIY Oscilloscopes, DIY Kits for Hobbyists