I had cause recently to whip up a dividing curtain to help keep in the heat and keep out the draught between a lounge and dining area. Here's how I did it using stuff around the house.
The curtain was made from old moving blankets, nice and heavy for the purpose but you can use whatever you like.
Use a takeout container lid, so you can see through it to place the diamond pattern.
Cut out three squares the same size and place them as in the photo so your pattern will fit. My squares came from thin polystyrene packaging material from a parcel I got.
Glue down the side squares and remove the middle one. A tacky glue was used here. Stamp away with brush and paint, placing your design with your see through stamp.
Acrylic paint watered down to 'shaving cream' consistency worked really well. For this project there was no need to set the paint.
Try this on plain duvet covers, tablecloths etc. To set the paint on finer materials like cotton, wait 24 hours, place a cloth over the pattern and iron it on a medium setting.