Paint nail various colours (or search ombre nails). Apply nail striping tape (or cut reg. tape into stripes) in a design you like. Paint whole nail with black nail polish. Peel tape when just about dry (slowly).
Here is 15 Best polka dots nail art ideas for summer. Cute polka dots nails with bows and diamond Stylish black and glitter polka dots fall nails Red glitter polka dots nail art for Valentine’s Day Polka Dots Fall Nail