Reddit mentions of Helix Plastic T-Square 12 inch / 30cm (20002)

The third method is basically up to you. I can tell you from what I see, and what I am doing now, is simply one or two prints of each image. Size is completely up to you and usually based on the quality of the image of course. That is where you kinda play the game "will this sell at this size?". Usually, the bigger the better in the eyes of the consumer. If it is bigger, they will pay more, if it is smaller, they will pay less.

The third method is best used when you are attempting to grow your profit margin, as in the materials aren't to expensive if you do your shopping.

Here is a good idea of what it will cost you.

Elmers Foam Board 10 Pack of Black - $36.49 USD no shipping w/Prime

x-acto blade for Foam Boards - as low as 9 bucks, this is comes with 2 blades, and will last quite some time

Spray Adhesive - $6 cheaper in store

Cheap T-Square, nothing fancy needed - 4 bucks

Now, the T-Square, and Blade are products that can last a while. All Together you spend about $55 USD, at the swapper, for 8x10's, I saw prints going for $30 and they were selling.

You almost made your money back in one sell.

Gotcha, yes I know exactly what you mean. Right now I use this:

https://www.amazon.com/gp/product/B00290MIWC/ref=oh_aui_detailpage_o04_s01?ie=UTF8&psc=1

For my square. It's nice because the lip is very small - in fact it's smaller than foamcore so it always sits flush. The downside is I have to use it paired with a metal/cork ruler, because you can't really cut along the plastic edge of the square.

I wish there was a square with a metal ruler that would work. I purchased this:

https://www.amazon.com/gp/product/B00EXAAHT2/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

But it has the same problem you have, the lip is too big.