1.Create a sphere with a lat-long of 16.
2.Create a cylinder , and resize to 2.735m x 2.735m x 0.104m
3.Copy cylinder and resize to 1.900m x 1.900m x 0.325
4.Boolean Subtract Cylinder from Cylinder,1.
5.Move Cylinder to 0.000m x 0.000m x 1.150m
6.Resize Sphere to 2.0m x 2.0m x 2.988m
7.Right click on boolean subtract, and select Keep Drill
8.Select the sphere and subtract ring.
9.Move ring +0.427m along z axis and resize by -0.280m x -0.280m x -0.00m
10.Subtract ring(cylinder) from sphere.
11.Resize ring to 2.735m x 2.735m x 0.104m, and move to 1.000m on z-axis.
12.Repeat steps 8 and 9, reversing amounts.
13.Move ring to 000.00m x 000.00m x 1.000m, resize to 2.705m x 4.134m x 0.104m, then rotate 90° along x-axis.
14.Subtract ring from sphere.
15.Rotate ring 45° along y-axis, and subtract from sphere.
16.Repeat step 15 2 times.
Your grenade should now look like this:
Notes:
If Bool Subtract doesn't work, try Boolean Intersect, or Boolean Add.
The meters(m) sizing can always be replaced with your own.