This little creature crawls towards the light, using its sensitive cheeks. You can direct its path by throwing a light beam at it. It is based on a Velleman Kit and customized with a crab-shaped coat to give it a plushy look.

Crawling Microbug from Piem Wirtz on Vimeo.

Tools
Soldering iron
Solder
Small tweezers
Small cutter
Fabric scissors
Needle and thread
Sewing machine (optional)
Hammer or Prym Vario Plier

Materials
Velleman Kit MK129
2x AAA battery
Heat shrink tubing (small size, black)
Red jersey
Red felt
Synthetic fibre fill
Tape
5 eyelets (Prym, ø 4mm)
Elastic cord
Safety-pin
Metal wire

Step 1: The Circuit Board

The hardware for this light-sensitive robot comes as a standard DIY kit. You can order it online and assemble it yourself.

1. Open the package of the Velleman Kit. Unfold the cardboard inlay.
Inside, you will find step-by-step instructions how to solder the parts onto the circuit-board.
2. Sort out all components and order them on your table. Identify the LDRs (Light Dependent Resistors, the ones with the spiraling pattern) and put them aside.
3. Solder all components following the Velleman instructions, but do not solder the LDRs just yet! These are your light sensors, and therefor need to be placed on top of the fabric skin, piercing through it.
5. Solder the LEDs at the very end of their legs, leaving them sticking out on the other side. You want them to resemble snails eyes.
4. Cut two tiny pieces of heat shrink tubing and pull them over the LEDs legs. 'Brush' over the tubing with the hot soldering iron. The tubing will shrink around the legs, making a more robust assembly.

Tip: Soldering the motors can be tricky if you are new to soldering (you have to fill up a gap). It will help if you apply solder on the board and on the motor first, and then connect them together.

Step 2: The Coat

I will describe a general how-to for the coat, of course you can customize it to your taste and go crazy with all body parts.

1. Take a piece of jersey and trace the shape of the circuit board. Add two cm on all sides. Cut it out.
2. Make a tunnel in the jersey by folding the edges to the inside. Pin it and stitch it. Use a stretch-stitch for best results. Make sure you leave 1cm open.
3. Attach a safety-pin to the elastic cord and gently push it through the tunnel. Pull the cord on both ends to wrinkle the skin, thus creating some sort of 'shower cap'. Tie the two ends together.

Tip: Pin the other end of the cord to the 'entrance' of the tunnel to avoid the cord is accidentally pulled through (and you have to start all over again…).

4. Trace the shape of the circuit board again and cut it out of fibre fill.
5. Cut six legs out of felt.
6. Cut six pieces of metal wire and push it through the felt. Bend the legs.

Step 3: Assembly

Now you are ready to combine the textile parts with the electronics.

1. Cover the fibre fill above the motors with a piece of tape. This will prevent the fibre fill getting tangled in the spinning 'legs'.
2. Insert the batteries.
3. Position the jersey cap above the circuit board. With a felt-tip pen, mark the spots where the LEDs and the three variable resistors (the black rods pointing upwards in the 'neck') poke through the fabric.
4. Place the fibre fill into the jersey cap.
5. Make small holes through the jersey and the fibre fill and apply the eyelets.
6. Gently pull the cover over the circuit board, guiding the LEDs and resistors through the eyelets.
7. Sew the legs to the body.
8. Pierce the LDRs through the fabric and through the holes in the circuit board. Solder them at the bottom-side of the bug.
9. When you are done soldering, switch it on. You will need to lift the jersey a bit, or feel for the switch underneath it.
10. Test your light-sensitive robot in low light conditions, and point a flashlight at it. When the light reaches the robot, it should start moving.

Tip: You can adjust the sensitivity of the light sensors and the speed of the 'legs' by fiddling with the three variable resistors.