First mix Jello by box directions, except use reserved pineapple juice in place of part ... scrape and grind carrots (or chop in blender) and ... refrigerator to set firm.
Drain pineapple, reserve 3/4 cup juice. Dissolve Jello in hot water, add mayonnaise ... set. Fold in carrots and pineapple. Chill until firm. I use 8 inch square pan.