I watched a sci-fi film on British TV early or mid-80s.
Theres a man, potentially with blonde hair who gets put into a container exactly the same shape as him. Needles go through the container and inject him with something to supposed to transform him or improve him. It’s really painful for him and theres psychedelic colours everywhere while it happens.
Bit of long shot, but could this be the Acid Queen sequence from Tommy? https://youtu.be/2rJGX8uqoL8