Move over fidget spinners - "slime making" is the new thing keeping kids occupied.
And although it can help them develop science and business skills, they need to be careful, an expert warns.
Young Kiwis are making the stretchy goo using instructional videos on YouTube and some enterprising children are selling their creations online.
Fans of the craze, Honor Mitchell, 9, and sister Alice, 7, from Westmere, told the Herald on Sunday they like to make slime because it's fun.
"It's really satisfying when you have it," said Honor.
The girls' friend and neighbour, 8-year-old Katie Baber, often made slime with them.
She said the best part of the process was "watching it form", but she wasn't allowed to make it as often after ruining a few chairs and the carpet with her experiments and blocking the sink one weekend.
Takapuna resident Libby Haskell's 12-year-old daughter Alice started making slime a couple of months ago.
After Alice became "quite obsessed" with it and her mum became frustrated, Haskell suggested she sell it online.
Using her own money to buy supplies and managing the purchases through her mum's TradeMe account, Alice was learning organisational and budgeting skills.
"We're not going to make our millions doing it but it's quite fun. It's a pretty easy thing to do," Haskell said.
"We're actually trying to work out from a bottle of shaving foam how many slimes can you get out of it? What's your profit margin?"
The main ingredients in most slime recipes are glue and borax - a product you can buy in DIY stores that is used in most detergents - and retailers are cashing in on the craze.
Peter Darbyshire, Warehouse Stationery's general manager of technology and stationery, said the chain had seen sales of PVA glue quadruple since last year and it was because of the popularity of slime making.
Stores were having to order more glue to keep up with demand and team members at some stores were building "slime stations" with ingredients and accessories purchased to make personalised slime - like pom poms and glitter and paint.
The owner of Hammer Hardware's Hauraki Corner shop, Erik Jones, told the Herald on Sunday he had started selling smaller 100g bags of borax for $3 each after slime making took off.
He said staff were initially hesitant to sell borax to children because it was used in ant bait but changed their minds when they realised they only wanted it to make slime.
"Generally speaking, we asked them to bring their mums along with them but because of what the kids were doing with it, we actually decided that in small quantities it was okay."
Although a basic slime can be made using a borax solution and PVA glue, other YouTube recipes for different variations require kids to mix potentially dangerous chemicals such as nail polish and cleaning products.
Earlier this year an 11-year-old girl from Massachusetts who regularly made slime, Kathleen Quinn,reportedly got second and third degree burns from extended exposure to chemicals.
Science educator Dr Dave Warren told the Herald on Sunday although borax wasn't usually dangerous, it could sting your eyes and should still be used cautiously.
"You probably need to know what you're doing if you're going to go down some of those routes and just because on YouTube it doesn't mean it's safe and they're something you should try," said Warren, who has been teaching school children for about 10 years to make slime safely through Otago University's Chemistry Outreach programme.
"The general rule I'd say is avoid anything like that unless you know what you're doing or you've got somebody who can check it out with some sort of expertise."
He also recommended children wear safety glasses when making slime. "I wouldn't just let the kids do it. I would watch them with it. Just in case something goes wrong."
• Make a borax solution by combining 1tsp of borax with 4 cups of water
• Mix equal amounts of good quality PVA glue (from an art shop is best) and the borax solution in a ziplock bag or plastic cup for a few minutes (ziplock bag means less mess)
• If you want a tougher, more stretchy slime add corn flour, 1tsp at a time
• You can also make a bouncy ball by putting the slime inside a balloon and tying a knot
• Don't forget the safety glasses