In star and kaleidoscope blocks six or more seams meet at the center. If you don't plan ahead for the seam allowances at the center puckers and bumps will probably appear. A simple trick will help to make seam allowances lie as neat and flat as possible.

While sewing both block halves make sure to iron all the seam allowances in the same direction. It doesn't matter whether clockwise or counterclockwise.

Finish sewing the last seam. Loosen stitches marked in red within the seam allowance as shown in the illustration. Do not cut the threads! Repeat on the reverse side.

Now turn the last seam allowances according to the chosen circular seam direction by ironing one half up and one half down. Omit the center.

Now you will be able to form the rosette with your finger tip in the middle of the seam allowances.

The same principle applies when piecing the top. Make yourself an ironing plan before you start sewing.

Sometimes it is impossible to turn all seam allowances the way you want them to go. In that case you may want to make a short diagonal clip into the seam allowance to be able to change its direction.

And last but not least: sometimes it might be a good solution to hide the critical point behind a button or yoyo ...

A note about paper piecing: the seam directions are determined by the given sewing order. Check whether you can change the pattern to your needs or if you can change the direction of individual seams.