This is my basic lego R2/R3 unit. I used just the Legos I had on hand, this is why it's not one specific color. This is my own original design except for the dome part which I got the direction for out of a lego book.
I made diagrams of the entire model and took pictures of the building process.

The way I have wrote the directions is to build the body by building the dome first on a large lego board, removing the dome from the lego board flipping it over and building up the main part of the body.

After building the main body build two legs. I only drew out this diagram once because the leg are identical.

Each diagram is labeled. for example layer 1of the dome is labeled layer 1a, the first layer of the main part of the body is labeled layer 1b in the diagrams, and the first layer of the legs is labeled leg layer 1

Finished size: 5" front to back, 8 1/4" side to side and 9 1/2" tall.

Step 1: Layer 1a,

The dome layer for this layer you will need
Eight 1 by 4 bricks
Four 1 by 3 bricks
Two 2 by 6 bricks
Six 2 by 2 bricks
Four 4 by 2 bricks
See diagram and photo for assembly

Step 2: Layer 2a

For this layer you will need the following bricks
Four 2 by 4 bricks
Four 2 by 3 bricks
Four 1 by 3 bricks
Eight 1 by 4 bricks
Eight 1 by 1 bricks
See diagram and photo for assembly

Step 3: Layer 3a

For this layer you will need the following bricks
Eight 2 by 4 bricks
Twelve 2 by 1 bricks
See diagram and photo for assembly

Step 4: Layer 4a

For this layer you will need the following bricks
Eight 4 by 2 bricks
Two 8 by 2 bricks
Two 6 by 1 bricks
Eight 2 by 1 bricks
Four 1 by 1 bricks
See diagram and photos for assembly

Step 5: Layer 5a

For this layer you will need the following bricks
Two 2 by 6 bricks
Two 4 by 1 bricks
Two 6 by 1 bricks
Eight 1 by1 bricks
Four 2 by2 bricks
See diagram and photos for assembly

Step 6: Layer 6a

For this layer you will need the following bricks
Two 2 by 2 bricks
Four 1by 1 bricks
Two 6 by 2 bricks
Two 1 by 2 bricks
See diagram and photos for assembly

Step 7: Layer 7a

For this layer you will need the following bricks
Two 4 by 2 bricks

Step 8: Layer 1b

This is a picture after layer 1b has been completed
For this layer you will need the following bricks
Sixteen 1 by 4 bricks
Four 2 by 2 bricks
See diagram and photos for assembly

Step 9: Layer 2b

For this layer you will need the following bricks
Twelve 2 by 2 bricks
Four 2 by 4 bricks
See diagram and photo for assembly

Step 10: Layer 3b

In this layer the pieces highlighted in pink are technic pieces. See picture
For this layer you will need the following bricks
Two technic 1 by 4 bricks see picture
Four 2 by 2 bricks
Fourteen 1 by 4 bricks
See diagrams and photos for assembly

Step 11: Layer 4b, 6b, 8b, 10b, 12b, and 14b

For each of these layers you will. You will need following bricks
Twelve 2 by 2 bricks
Four 4 by 4 bricks
For assembly see photos and diagram

Step 12: Layer 5b, 7b, 9b, 11b, and 13b

For each of these layers you will need the following bricks
Sixteen 1 by 4 bricks
Four 2 by 2 bricks
See diagram and photos for assembly

Step 13: Leg Layers

For the following layers you will need the following bricks
Leg layer 1 & 3 per layer
Five 2 by 4 bricks
One 1 by 6 brick
One 1 by 4 brick

Leg layer 2
Four 2 by 4 bricks
Two 1 by 4 bricks
One 2 by 3 brick
One 2 by 2 brick

Leg layer 4
Four 2 by 4 bricks

Leg layer 5, 7, 9, 11, & 13 per layer
One 2 by 4 brick

Leg layer 14 & 17
Two 2 by 4 bricks
Two 1 by 2 bricks

Leg layer 15
One 2 by 4 brick
Two 2 by 3 bricks

Leg layer 16
One technic 1 by 4 brick
One 1 by 4 brick
Two 2 by 3 bricks

Leg layer 18
One 2 by 6 brick
One 1 by 6 brick
One 2 by 2 brick
One 1 by 2 brick

Leg layer 19
One 2 by 4 brick

Make two legs by this pattern see diagram and photos for assembly

Step 14: Bottom of Body

This step is not necessary but I choose to put some random plates on the bottom. See pictures if you want to complete this step.

Step 15: Assemble of Unit

To assemble this unit you will need two conecters for the technic pieces see picture
Put a technic connector in the center hole of the technic piece of each leg see picture for reference
Now attach the the legs to the body. Do this on both sides, then sit back and admire your work.