Dụng cụ gắp Petling (Nam châm nhựa)

Tool specifically made to extract a Petling from a tube (with a minimum diameter of approx. 46 mm)

To assemble the gripper, use:

3x M3x16 mm hex bolts
1x silicone O-ring approx. 23 mm ID, or a rubber band.

String version
1x flag line, wire or similar with a max Ø of 5mm, feed through threaded hole and put a knot on it.
1x lead weight as found on old fishing nets (75g, H: 28-29mm, Ø: 22-23mm, inner bore: 6mm)

Extractor version:
1x M6x20 mm hex bolt (if that is your extractor configuration)
or use the built-in 6x1mm thread

Print GripperHousing with supports. 0.2 layer and clean up 3mm holes with drill bit. Or finer resolution and no clean up.

Adjust gripping power by moving the O-ring/rubber band to a different groove in the arms. Make sure the arms are moving freely before applying the O-ring/rubber band.

Purpose built for this cache: https://www.geocaching.com/geocache/GCBR11W_petling-i-ror 
Should work for this cache as well: https://www.geocaching.com/geocache/GCBTKHR_petling-i-ror-hastrupvej