If your like me and don't have any big power tools at home like a router, band saw or lathe but need basic shapes for your carvings; here is a trick I learned on how to make a circle from a square.
well more accurately a cylinder from a cube (photos a bit crap, hard to show details with solid white)

Side note: The left side is sanded, the right is not...for comparison
(Not really the right side was done to see if my instructions could make my wife with 0 carving knowledge pull it off)

Once you've mastered properly rounding an edge you can accomplish a lot more then you think. Like the fellow below.

As much as I love the art of making everything by hand, if I need more then one basic shape that my medium doesn't come in, its a real time consuming pain. Like the pretty little robot. If I win this CNC I'll get more done quicker......and probably more accurate, almost machine like accurate :-)

Hes a Destroyer from War Machine - my 2ft version scaled up model from his 2in table top original as a concept model for a larger life size version that never got approved. So its an up scale for an up scale!

Step 1: Step 1

What I'm about to show you was taught to me by the great Ivan Saxby
I call it the half of the half rule
bear with me it'll make sense as we go

For this task I'm using:
High density foam
Ruler
Marking device (pen preferably, sharpies make to large a line)
a sharp blade
and some sand paper
(sand paper I use for this particular foam medium is 80 grit then again w 120)

Start with your basic Cube.

For the demonstration I will be working on 2 sides A & B and of course top and bottom

Step 2: 2

First step is find the center of your surface or the half way mark.

Step 3:

heres where it gets to be a confusing read

Once the halfway mark is done you will need to find the halfway point from the center
Do this on all 4 sides

if your brain hasnt exploded yet you should have 3 markings per side at the 1/4 the 1/2 and 3/4 of your surface

go threw the photos if your confused and hopefully it will make more sense

Step 4:

Once you have the markings in place, repeat again on the bottom

once your measurements are in place connect the top and bottom markings with a straight line using a ruler (not the center marking)

Step 5:

Go to the top of the cube and connect the nearest marking to each other. It should make triangles on the edges of your cube.

This step will help you place your blade better

Step 6:

Now you have successfully measured and drawn your first cut lines, now slice off the corner. Go slow because you cant put it back once its gone!

Step 7:

Here is what you should have

Now find the Center point of the new area and mark it

Step 8:

Now on the newly cut surface find the half way mark between the center and the edge and mark them

On Side A find the half way mark between the new edge and your original center marking

On Side B same thing, find the new half way mark between the new edge and the original center marking

starting to understand my half of the half rule yet?

dont forget to mark the top and bottom

(shown is not 1/2 inch just the half way point)

Step 9:

Connect the top and bottom markings again with a straight line

don't forget to mark the top as well

Step 10:

and remove said areas

draw X's on areas that need to be removed to avoid confusion or if you suffer from brain farts like I do

Step 11:

almost done

with 3 cuts you've turned a square edge into a roundish one

Step 12:

to finish it off completely just run some sand paper down the edges to remove the hard lines and your good to go
sand paper to use for this particular foam medium is 80 grit then 120 for best results.

its a bit of work but if everything is measured properly you'll have it every time.

Side note: The left side is sanded, the right is not
(for comparison.....not really the right side was done to see if my instructions could make my wife with 0 carving knowledge pull it off)