Using Masks and Layers—Painting, Filling, and Color Tools - GIMP 2.6 for Photographers: Image Editing with Open Source Software - page 239

Access the Brush Editor to create a new brush. Select a radius of 300 px
and a feathering of 100% ( Hardness = 0.00). Reduce the spacing to 10 to get
an even brush stroke. The Spacing value indicates how many painting dots the
brush produces within a certain distance. Use a large, round brush with full
feathering when painting surfaces without transitions.
In the tool options dialog, set the opacity for the brush application to a
value of about 10%.
With these settings in place, you should now paint in semicircular strokes,
one stroke after the other. For the lights, start at the tip; for the shadows, start
at the bottom of the object. Begin painting outside the egg; don't worry
about staying inside the line. The outside area is protected by a mask. Paint
across the object in steady strokes. While painting, hold down the left mouse
button, release it after each stroke, and apply it again. If you want to increase
the opacity at the bottom of the shadow, you can repeat this process several
times.
Use a smaller, softer brush to set a light reflex spot on the lighter area. You
may have to repeat these strokes if you want to achieve a uniform application
of color.
The Eraser tool may be helpful. It works similarly to the Paintbrush tool.
You can reduce the pressure sensitivity/opacity in the tool options dialog so
that you can erase in “fuzzy” strokes rather than erasing everything at once.

• NOTE
Create a separate layer for each
lighting effect. If something goes
wrong, you can simply discard that
layer and start fresh.

3.9.5 Overview of Part 2—Inserting, Duplicating,
and Colorizing Image Objects

Before exporting your Easter egg, you'll want to add a drop shadow. Moreover,
all layers should be reduced to one (otherwise, you will need to export,
position, and touch up each layer individually). Below you'll find an overview
of the steps involved.
In another section, I will discuss the subsequent re-dying of image
objects, which in this case would save you the work of creating the egg again.
• The shadow that the egg would naturally cast onto the ground is missing,
so you'll have to create that effect. First produce an elliptic selection with
a soft border of approximately 75 pixels ( Select > Feather ). Fill the ellipse
with black by selecting the Bucket Fill tool or, alternatively, the Edit > Fill
with FG Color menu item. Delete the selection. Make sure the layer is
positioned beneath the egg layer in the Layers dialog. If it is not beneath
the egg layer, use the Move tool to reposition the shadow layer.
• Save the image as workingegg.xcf .
• Delete the Background layer (white background) by selecting that layer in
the Layers dialog and clicking the Delete button (garbage can icon).