The Dremel Drill Press workstation has instructions on making a set of carriage bolt based hold down clamps.  I made these with my 3D printer instead.  A couple of caveats.  One, these are light duty only, just enough for insert press duty.  Two, there is some DIY work needed such as to remix the model to your left-over scraps and the parts you decide to use.  In my case, I used discarded rivet mandrels to provide pivot rods by cutting them to size then super-glued them in.  The pivot part's hole is a little smaller providing a friction fit, glue to that.

You can also add a spring and extra washer which makes it one handed use but I didn't need that.

Feature:

• Flat edge can be used as an end post.
• Can hold up to 1½" tall items.

Build Recommendation:

1. Superglue nut to knob.  Then…
2. Wrap the carriage bolt with painter's tape.  This will protect from superglue run-off as the bolt acts as stop for the pivot rods you've just made.
3. Place glue in the pivot part's pivot holes.
4. Assemble pivot part with arm part ensuring pivot holes are aligned.
5. Spray activator on to your rods, then press them into pivot holes so that they aren't proud of the side.
6. Remove the bolt, take off the tape.

… and Bob's your uncle.

Hardware:

• 5/16-18 x 2" carriage bolt
• 5/16 washer
• 4/16 nut
• x2 dowels (discarded 3.6mm Ø rivet mandrel, cut to size)

More Slicer Info:

• Perimeter/Ends: 6/8
• Infill: 20% Rectilinear
• Manual supports (see illustration)