Karma is the emotional baggage left over from past events.
Art, is emotions made into form of expression.
So, doing art - any kind of art - is a good way to get the stuck emotions out of you, and into some form that you can then give away, burn, or cherish... so long as you do not go from an attachment to the karma, to an attachment to the art!
The idea of art therapy is intimidating to some people, who feel that they are not artistic, and get all caught up in expectations of themselves, the art, and fears of not being good enough.
Set all that aside, it is quite beside the point of this exercise. Surrender your fears.
In many native cultures, like the Eskimo-Inuit, the responsibility for the quality of the art, does not lie with the artist. If an Inuit wants to carve a seal, he will go out and find a stone that looks like it might have a seal in it, and take away the stuff around the seal, so it is revealed. If the sculpture turns out not to look much like a seal, the artist's friends won't say "you did a bad sculpture." They will say, It looks like that seal did not want to come out! He gave you a hard time, eh?" They will laugh about the stubborn seal spirit who did not want to come out of the stone.
The artist is the medium, the vessel that the art comes through. Some of the very best artists, consider themselves to be nothing more than a slave to their muse. That attitude, is part of the secret of great art! Even Michaelangelo said of his sculpture "David", that he found a block of marble that looked like it might have David in it, and carved away all the bits that were not David, till he appeared!
This is also a lovely metaphor for the Kundalini process. Kundalini releases all the karma and stuck ego bits, the "social mask" that hides your true Self, until you appear! Carving away the bits that are not the real you (though your ego may think they are!) until at last you, your Real -(ized) Self is all that remains.
I do not care what kind of art you do, or how good or bad it is. You do not care either. Shakti is creative energy, let Her worry about the quality, your job is simply to allow the emotional karma gunk to take form.
Doodles on the back of an old envelope, mud pies or egg carton caterpillars, it matters not at all. The art, is in the doing. Fancy art supplies, oil paints and brushes are not required for this, don't let the lack of them stop you. Use them if you feel like it, but sometimes it is nice to complete the release process by burning the result, and some art supplies don't burn very well. Plasticine in particular comes to mind.
For an example, I'll use drawing. Sometime when you are having a hard time releasing an emotion, get a blank sheet of paper and a pen or pencil. Sit relaxed, with the pen on paper, and focus on the emotion. Ask yourself, "what would this emotion look like, as a drawing?' Ask Goddess within you to help you to transmute the karma into art.
Pretend your hand and arm belong to someone else, and you are watching them draw... or just start to scribble whatever. If you are having a hard time letting go control, then use your non-dominant hand, the one you usually do not write with, is the one more closely connected to the unconscious.
Let the art come through you, instead of trying to control how you want it to look. Allow yourself to be surprised, and do not be disappointed if what comes out is scribbles. Stick with it, until your hand comes to rest, by itself and you get a feeling of completion... of peace, like the release is done. If you want to do several drawings in this way, go ahead! Allow yourself to play like a child.
You do not have to show the result to anyone, although you can, if you feel like it. You do not have to sign you work. You can throw it out or burn it, if you want... bury it, or make a scrapbook.
Drawing or doodling is the simplest and most accessible type of art therapy, but you can do whatever kind of art you like! Childlike art seems particularly effective, because you get to be childlike, and play! When was the last time you did finger painting? Made a sand castle, or a snowman? Played with wax crayons? Played with plasticine? Just mush it around in your hands, feeling the texture, until your hands start to sculpt it, all by themselves. Then squish it and make something else! Good therapy to make a model of what is bugging you, then pound it flat, so long as it is not a person. No mashing voodoo dolls allowed!
Let it be a creative exploration, with a sense of wonder at what your hands seem to be doing, all by themselves.
Any kind of art, or crafts can be art therapy, so long as you do not set your standards too high. Machine perfection is for machines, photographic realism is for cameras. So what if your quilt has crooked stitches or your doily is not round? If you make candles and they do not burn straight, it is a good excuse to melt them down again and make new ones. Melted, soft wax is very sensual on the fingers so long as it is not too hot.
The art, is in the doing. The result, does not matter. The act of doing the art will release the karma stuff, and that is what you want!
Watch the craft shows, there are all kinds of inexpensive crafts and hobbies that you can get into with minimal expense. A bag of mortar and some old boards, plus some broken glass or dishes, and whatever you have around will come together into an abstract mosaic. Mix the mortar and spread it on the board, like icing a cake, then start sticking the glass and broken dishes into it. Put in some leaves, egg shells, tin cans, toy animals, string, anything you like. Scratch patterns into the mortar before it hardens.
Make a sock puppet, plant a terrarium in a jar, knot some string into macrame, melt some old candles into new ones, whittle a stick, sew a hat, make a mask out of a paper bag, anything, anything so long as it is creative! Any kind of craft or art you can think of, Google search will provide a thousand websites with 'how to' info... and aside from safety considerations, you can adapt the advice, as you please! Feel free to colour outside the lines.
The exception, is cooking. Do not use cooking as karma release art therapy, because you will be putting your karma into the food, and it is kind of an energy poison, you do not want anyone to eat it! The exception would be making bread dough animals that nobody is going to eat anyway.