Bulldog clip with fixed flat back 38mm cover button
|mal & template 38mm, DIY fabric
95% same way like you would make a cover button 38mm.
Only difference is that you need only part of the mall (not the pressing device)
You need to press the clip with its flat back into the mall where you have placed your prepared (cut) fabrick until you feel (or hear) a click.
No glue needed here!