Screen cap image source ink:
Punch of Kill Everything - Transformers Wiki



Here is a parts list (also you can use a round button, as he used both in the cartoon):

Pick A Brick item names are:

(For an open version):
1x Connector Peg W. Knob Element ID: 4211483 Design ID: 4274
1x Flat Tile 1X1 Element ID: 307021 Design ID: 3070

(For closed version 1):
1x Brick 1X1 Element ID: 300526 Design ID: 3005

(or add for closed version 2):
2x Plate 1X1 Element ID: 302426 Design ID: 3024
1x Plate 1X3 Element ID: 362326 Design ID: 3623
2x Roof Tile 1X1x2/3, Abs Element ID: 4504382 Design ID: 54200


Super-simple punch of kill everything:



For this you only need 2 LEGO's (3 for the closed hand version 1, or 7 for closed hand version 2):




[To] assemble like the top one for open punch/bottom one for closed:




(Please note depending on how tightly you push it in you may need tweezers to remove this form his hand you can just leave the gray piece in there it will close with it in place)

There are two (2) lines that line up with the holes in the LEGO perfectly. Place the LEGO in, spin it till lit lines up, and your done:




Open version:




Closed Version:




Double Atomic version:



New version closed 2