The big issue I faced when I tried to create my own custom envelopes with just my scoring board was that sometimes my measurements would be off and my envelopes would turn out warped and wonky. I purchased this envelope punch board because I needed the ability to create custom envelopes for my custom-sized greeting cards and I needed them to be clean and professional. This punch board really delivers! I purchased it at Impress and paid $19.99. Stampin Up also sells a similar product - also made by We R Memory Keepers - for $21.95 plus shipping. The two products, from what I can tell, are exactly the same and the only difference is that the Stampin Up product has "Stampin Up!" in the far top left-hand corner.
So if you're a paper crafter and you need something that helps you to create custom, professional looking envelopes, I suggest that you spend the $20.00 and get this little beauty! It really is worth it!