How to make the shift channels only inside a print of a spider?

1) cut out the spider with a pen to get its shape.

2) cut a spider shape in the t-shirt.

3) paint the spider shape in black and make the shift channels.

4) remove the black color of the spider shifted, leaving a color shift.

The end result is two layers - a shirt with a hole in the spider shape and contour of the spider with the aberrations.

Please send the PSD, so I can't clear what method they were made.