I'm a fan of using VELCRO strips that have the mating textures on both sides.
Several 1/2" wide & 6" long help hold clincher tires in place as I work the beads over the rims. Never had need of anything but my hands for sew-ups, what I started with back in 1972 and what I still ride on my '72 MB Grand Record.
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"Bramo assai,poco spero,nulla chieggio."