The liner of our IKEA Branäs laundry basket kept sliding off when being filled. There are just loops and no way to tie them down. So I designed a quick corner piece with a post to hold the loop of the liner.

For rectangular baskets with 16mm wall thickness. For other sizes, just scale the model. The posts can face to the front or to the side, depending on the placement of your basket. For the opposite side just mirror the model in your slicer. 😉

Don't mind the warped corners on the images, I should have used a brim.

I used 15% infill, as there's not much stress on the part. Use supports, there's going to be just a small area underneath the post that needs to be supperted.