How to use the custom design app to make a checkered pattern with sharp corners?

I'm trying my hand at my first custom design. I want to make a red/pink/white checkered picnic blanket. Sounds simple, right? I made my design using the 3x3 pen tool, marking 3x3 squares in different colors to create the pattern.

I already noticed while I was designing, but as soon as I put my design on the floor, the corners are rounded and the blanket looks more polka-dotted than checkered.

Is there a way to create a checkered pattern, one that will keep the sharp corners?

Solution 1:

From the look of your blanket, I'd guess the problem is you're trying to fit too many rows/columns into a single tile - with the way ACNH patterns work, a 9x9 is going to lose a lot of definition and end up looking very blobby, as you've seen.

Square-looking picnic patterns exist, and most of them try to stick to around a 4x4 grid on any particular tile to make sure the pattern stays sharp when placed. See, for example:

(Source.)

As you can see, the creator sticks to relatively few squares per tile, and just repeats tiles to create the size they want. I would recommend not using the 3x3 pen tool directly to create your blanket, and instead using the tool to create larger squares.