The R&D TC100 paint thickness gauge from AliExpress isn’t expensive at all; you can use it on aluminum too, and it has over 900 orders

The process is via the AliExpress mobile app, where most people shop. There are two key things: don’t use Buy now and enter the coupon only in the order summary, in the field Promo code. After you click Pay now, you won’t be able to add it.

1. Copy the code and click Use discountIn our article, copy the coupon and click the button GET DISCOUNT. The link will take you directly to the product in the AliExpress app.
2. Use Add to cart instead of Buy nowOn the product card, scroll down and tap Add to cart. Don’t use the Buy now button—you’ll skip the cart, and later you won’t have anywhere to enter the coupon. Before that, double-check the variant: the color, the version, and whether it ships from an EU warehouse.
3. Through the cart, go to CheckoutA pop-up will appear: Added to cart! — tap Check it out in it. If it disappeared, open the cart with the icon at the bottom right. In the cart, check the product and quantity, then click the red Checkout. Only the items marked with the red ring will be applied.
4. Enter your address and card, then look for Promo codeIn the order summary, first fill in the delivery address and payment card at the top. Below them there’s a line Promo code — expand it with the arrow on the right.

   

5. Paste the code and confirm ApplyIn the field Promo code paste the copied code and click the black Apply. The code is case-sensitive and must not contain spaces.

   

6. Check the savings and payIn the Summary expand the line Saved — you’ll see the applied coupon there as AliExpress coupons/codes. Only when Total is really lower, click Pay now.