The trippy sixties vibe that looks a bit like that was created using mineral oil and water, plus water soluble dyes and oil soluble dyes. Since oil and water don't mix, you lots of weird shapes and colors that way. Then they'd place them in between a pair of round glass dishes and set it on an overhead transparency projector and manipulate the top dish to create the movement. Clock faces work well for the round glass dish. You might could try something like that, and then photographing the results.
Or, you could try exposing your negatives to various chemicals and see what happens to them. I'd probably play around with some oils and solvents to see what does what. Maybe even try some dyes. Just be sure do it in the dark, and don't send them out to be processed. Those extra chemicals could screw up everyone else's negatives that get developed after yours. So you'd want to develop them yourself and throw away the chemicals when done so not to contaminate other negatives. It would probably be good to start off with small test strips and see what does what.