Here is something I've been working on for a little while now, an automata that is based on the lotus flower. All parts are printed, including hindge pins. I am working on a smaller version that will use filimaent rivets instead of pins.  Currently the hand crank is too small to turn the load so the center needs to be turned by hand. I plan to add a motor to it. Stay tuned.

Assembly:

A. Assemble the base with small gears...
*Note the small alignment mark on the base, this is the "Inner Gear 1" mark.
*Note that all the small gears are marked. Outer gears are marked with rectangles and the inner gears are marked with circles. The number of marks corresponds to the gear number. Example: Outer Gear 4 is marked with four rectangles on its bottom.
*The gears should rotate smoothly but snuggly.
1.Start by placing Inner Gear 1, drive-post up, over the inner center post marked "Inner Gear 1". If it doesn't drop down over the center post, you may need to press down and rock slightly to give the alignment some help.
2.Next place the remaining seven inners on their respective post in a clockwise fashion. Keep track of Inner Gear 1 since you'll need it for orientation of the outer small gears.
3.Place Outer Gear 1 on the outer center post above and slightly to the left of Inner Gear 1. See the illustrations for guidance.
4.Place the remaing seven outer gears on their respective post in a clockwise fashion

B. Align the small gears...
1. Rotate all the gears so that their respective drive-post face towards the center of the base

C. Lock in alignment with center and ring gears...
1. I suggest starting with the center gear to lock in the inner small gears first. Gently place the gear, flat side face up, such that the teeth mesh with all eight inner gears, locking them in place.
2. Some slight misalignment may have occured. You can gently press down on the outside of a misaligned gear and spin it such that its teeth skip the large inner gear. Use this technique to align the inner gears just right.
3. Gently drop the outer ring between the inner and outer small gear sets. Press down and wiggle slightly to mesh all the gears together.
4. Align any misaligned outer gears using the skipping method mentioned earlier.

D. Snap each cog into place...
*Note that the cogs are not quite semetrical. It doesn't matter which way you chose to place the cog on the gear so log as you are consistent. I placed my cogs such that the shorter end faced outwards.
1. Start with the inner gears. From the inside of the gear set, take one cog at a time and slip onto its respective drive post. The base will flex a little to allow you to "snap" the cog in place if you tilt it slightly when pushing it inwards. It should not take much pressure to get the cog to go in. Use patiece as you can snap a drive or center post in this part of the assembly.
2. With all the inner gears in place, twist the center gear and rotate all the small gears such that their drive-posts point outwards.
3. Place the cogs on the outer gears using the same technique as before only come in from the outside of the gear set.
4. With all cogs in place you can now rotate the center gear to watch a the cool parts move. Return the center gear to a position such that the cogs all point inward.

E. Pin the Inner Petals
1. Place a smaller inner petal into the cog gear such that the last "half-tooth" of the petals gears covers the last tooth of the cog. This can be a little tricky, but it wants to be aligned this way once you get it. The petal should be in the "opened" position if the cog is pointing inward.
2. Slip a pin into the base and petal to lock it in place.
3. Repeat the process with the seven remaining inner petals.
4. Repeat the pinning process with the 8 outer petals. The last petal might be a little tough, tweezers can help. Don't press too hard on the other petals when trying to get the final pin in, you might break something...I broke something :P

F. Add Center Piece
*This piece is optional, I made it so future center-pieces can be used in its place. Maybe a picture holder or ring tree?
1. Place the Center Piece into the square hole in the center gear.