I realize that a few pattern makers here have used patterncooler and I wanted to give it a try, unfortunately, this site exports the patterns in 80x80 pixels, and the patterns used for sims must be 256x256.

How did you guys work around this issue without having stretched patterns? I have no clue where to begin!

you just do image size, 256 x 256. Because they are vectors there isn't a lot of quality loss with a small jump like that. I work with mine blown up to 600 x 600 then shrink them down afterwards but I don't do them the same way as the tutorial here. Images are different to vectors in the way the pixels are worked, so you just don't get the same loss of quality

Thanks for the tip! Unfortunately, I screwed up, the patterns are exported as different sizes many times, but sometimes they have odd sizes like 450x260 which is where the stretching occurs...

unfortunately I guess there isn't a way to resize a 450x260 sized image to a 256x256 without some amount of stretching, right?

When you have a rectangular pattern that you want to convert to square, you have to squish it, or crop it, or some combination... for instance, tile it till you get something close to a square and then squish it. What works best depends on the pattern. Squares and circles don't look good squished, for instance... it's usually very obvious if you've done that.

For 450x260, I would probably copy it once to get 450x520, and then squish, if it is not a pattern that would look right cropped.

Be aware that almost all the Pattern Cooler patterns have been uploaded here before, some multiple times... in particular, Gangreless has uploaded dozens of them. Which is not to say you can't use them as a basis for a pattern, but definitely look at the patterns we have and make your upload different in terms of scale, texture, number of channels, or other features.

Or better yet, use another source There are lots of great tiling pattern sources on the web, and also tutorials on how to make your own. IMO the Pattern Cooler type patterns are pretty limited in their usefulness... a certain style of retro "mod" wallpaper or textile, mostly... and we have a LOT of that sort of thing already, because, let's face it, they're easy to separate.

Just as a warning, as Srikandi said, I have done literally all but about 3 or 4 of the patterns at patterncooler.com. Before you go to make one from there, I would check out the 26 part series I have to make sure you don't do one that I've already done.

Yes, I was using the pattrns on pattern cooler to make fabric textures. There are many patterns, but none of them seem to have any texture added for furniture or bedding, so I browsed some patterns of interest and overlayed a seamless texture to go with them, I also tried to avoid patterns I know have been uploaded to mts2 as much as possible. Especially the damask! :D