Today, I will show how to make a lifesize BB-8 with a budget of around 100$. It doesn't move, but it looks very cool for display. First, you will need these materials:

a 50cm/20 inch diameter styrofoam ball. (Overjoyed) (35$ + 35$ shipping)
a 30 cm/12 inch diameter styrofoam HALF ball. (Micheals or Overjoyed) (20$)
a 30 cm/12 inch styrofoam disk of 1 inch tick (Micheals) (10$)
a 3D Printer (for the black parts that you can see) (Already have it)
paint (5$)
a sharpie

Step 1: Draw the Shapes on Your Ball (and the Head!)

Before drawing the shapes, be sure to sand your styrofoam, because there a lot of imperfection on it.

For the shapes, look for some pictures on the internet. To make the the round shapes, I took large kitchen bowl and draw around them with a pen (for all the round shapes => different size of kitchen bowl). For the gray parts, I used pictures from the internet and draw them the most accuratly possible.

Step 2: Painting

After drawing the shapes, the next logical steps is to paint your bb-8. I choose Orange, White And Gray from Home Depot to paint it. An easy step, that takes patience.

Step 3: Head Details

For the bottom of the head, I used my styrofoam disk and cut the inside to make another layer under it. Then I sand these two layers at angle. For the middle part, I used a foam band and cut it about 2 cm tick. I glued all the parts together.

Step 4: 3D Printed Parts and Antenna

For the accessory parts, I used my 3D printers. There is other tutorial online about making these accessories without 3d printers so it is not a lost cause! You can find all the files here. (From BB-8 Builder Club). After the print you can simply make hole in the head with an Xacto and glue the printed parts on the head.

For the antenna I simply used a solid wired that I found in my garage.

Step 5: Last Details

The the round, engraving and details I simply used some Sharpie pen. I used the bottom of it in angle to engrave the gray details. And I color around the circles. Simple as that!

Step 6: Result

An easy DIY project for everyone who like Star Wars. It doesn't cost a lot and it looks very good! You can even add sound or LED to it. Hope you enjoyed it, any comment is welcome.