The 10% off DIY bundles promo code at the top of this page is the quick pick when the item in your cart is one of the selected DIY bundles and you can enter a promo code at website checkout. Use that code on eligible DIY bundle products to take 10% off the item price.
If you want a long subscription: take the $86 off plus free tools pack with the 1 Year Wacky Robots Plan. That fixed dollar saving and the included tools pack are aimed at annual subscribers and will usually save more than a flat 10% code on a yearlong purchase.
If you plan to buy a single kit like Wacky Genius or Wacky Master: pick the item level sale. Wacky Genius is 20% off and Wacky Master is 12% off, so those sale prices will generally beat the 10% DIY bundles code when you are buying those specific kits.
If getting extra kit extras matters: choose the complimentary gift with each bundle order when the free item is something you want, because that added item can be more useful than the 10% discount on the bundle price.
If your purchase is a different subscription length, pick the dollar off deal that matches it (for example the 6 Months plan gives $30 off and a free tools pack, the 3 Months plan gives $9 off).