Spray paint both faux pumpkins with the color of your choice. Tape off any areas that you don't want painted. Give several light coats and let dry. Let the pumpkins dry for 20 minutes. Once they are fully dry, inspect your faux pumpkins and make sure you hit all areas with the paint. If not, go ahead and fill in at this time and let dry completely.
Use images of the Star Wars droids to draw patterns on the faux pumpkins that you'll fill in. Use painter's tape to keep the lines straight.
Then I took R2-D2 outside again and spray painted the top silver. I thought that would be easier than using a silver paint marker and much faster. After the spray paint dried, I used my paint markers to start filling in the details.
Use the paint markers to start filling in the details. Let dry between layers and when switching marker colors. The paint markers go over the spray paint easy. Just make sure not to smudge what you've done with your hand before it dries.
Cut legs for your characters (if required) out of foam board using the craft knife. Add details with paint pens and let dry.
Attach the legs to the pumpkin using paper brads. You can use an awl to make a hole in the pumpkin if needed. Insert and position in whatever way you like.
Notes
It is better to use light coats than thick coats for spray painting.If you mess up: it helps to have gold and white paint pens (or whatever your base colors are) so that you can color over any mistakes. If you mess up, let the paint dry before going over it. You can go over it with acrylic paint as well. Brush several layers and let dry between layers.