Enginediy's headline offer is the featured voucher code for 10% off sitewide, which works well as a catch-all saving for most shoppers. That said, the store also runs several product-specific and multi-item deals that can yield substantially larger savings depending on what you're buying, so it's worth checking which option will save you the most before you check out.
Buying single items on general sale. The sitewide 10% voucher code is your best bet here, giving you a reliable discount across the full catalog. If you're eyeing the Turbofan Engine Model Kit or the Retrol Antique 4-stroke, however, check whether the 30% and 20% product-specific deals (respectively) are still active on those items when you browse—either of those will beat the 10% code significantly.
Buying two or more items. The buy any 2 get 15% off deal becomes your biggest saver the moment you add a second item to your basket, assuming neither item is excluded. A 15% discount on two items will outpace the 10% code by a clear margin. Run the numbers quickly at checkout to confirm, but in almost all cases the multi-item offer will come out ahead.
Shopping for specific products. If the Turbofan Engine Model Kit or Retrol Antique 4-stroke are in your sights and you're not buying anything else, their respective 30% and 20% discounts leave the 10% code in the dust. Just double-check the product listing to make sure the sale is still running, since these offers cannot be stacked with anything else.
First-time shoppers. Sign up to the Enginediy newsletter before you shop; subscribers often see exclusive promotions that may sweeten the deal further on your first order.
Only one offer applies at checkout, so compare what you're buying and take whichever option gives you the larger saving. The 10% code covers you across the site, but the 15% and 20%+ product-specific offers will usually outperform it once you have more than one item or you're targeting a discounted product.