While making a tyvek bivy, I didn't want to perforate it at all.
Others may face the same when working with cuben, to hold things in place while glue setting, etc.
I ended up using a number of pairs of very strong rare-earth magnets.
This worked really well, left no perforations, would allow me to shift the "pin point" by sliding them past where I needed to work and also helped in clamping the seams.
Downside: They're not light, and might be bulky when working with a sewing machine unless you have a large table.
Upside to the downside, if you're sewing you probably don't care about pinholes anyways.
-mox
