Some aspects of the LEGO production process are not publicly documented in enough detail to establish precise design rules. Therefore, I made some assumptions based on the general principles of injection molding and pad printing:

Overmolding and side actions are more expensive than creating two separate molds.
Pad printing from four different angles on a character is more costly than overmolding.
Pad printing cannot reach deep undercuts if applied from the same direction as the mold.

Solving the mystery of how this part was made led to the assumptions about pad printing. It has pad printed Horns but overmolded ears.

Rayla's hair

Finding a solution for too many colors

Process: Overmolding + basic (no side actions)

Overmolding is necessary for many elements based on characters in media, as they are designed without the constraints of the production process. Rayla's ears are smaller than other LEGO elements and positioned in a way that does not easily allow pad printing, making overmolding essential. However, this is not required for the horns. Rayla's hair allows for some creative freedom without losing recognizability, creating enough space to insert a separate element.

Not only does this reduce production

costs, but it also allows for greater

customization. For example, a fantasy

character could have antlers instead

of horns.

Twig

Matching the LEGO aesthetic

Process: Basic (no side actions)

Most LEGO animals are designed to stay within the width of the bricks that support them, resulting in a more blocky appearance. My goal was to translate a very rounded character into this blocky style.

A significant challenge was finding a pose that eliminated undercuts. To achieve this, I designed the ears to face outward. This still allows a minifigure to stand next to Twig, as he leans forward on the stud he can be placed on, giving the ears just enough room.

Zym's Dragonhead

Dealing with difficult angles

Process: 3x Basic (no side actions)

I initially expected this model to require side actions due to Zym's hair being at complex angles. However, after experimentation, I realized I could achieve all those angles with just one core and cavity.

LEGO designers often design dragon heads to be released from the mold vertically. However, the hair required a horizontal release. I solved this by incorporating existing bricks between separate sections instead of relying on a more complex mold.

The result is a three-piece design that is cost-effective to produce, though the hairpiece has limited functionality in other LEGO sets.

Red Panda Meilin

Adaptability

Process: Basic (no side actions)

I originally planned to create a more organic LEGO piece for this project. However, during the pre-sculpting modeling stage, I found that a flat head was a better fit. The design remains organic apart from the flat head, which just proves the importance of keeping an open mind during the design process.

I initially expected to need a slider to create a connection point at the bottom of the head. However, I realized that for a buildable big fig, a ball joint could be sufficient.

I recommend using prints instead of overmolding, as the ears could be printed white only on the front. This way, all prints can be applied from the same angle.

Can you guess the best parting line? (This is a textbook example!)

Teemo

Odd head for hats

Process: Overmolding + Basic (no side actions)

It seems obvious to create Teemo's head and hat as separate pieces. The parts are large enough, and the width of the hat would limit design flexibility for the face due to undercuts. However, this approach presents a challenge: the hat should be compatible with other LEGO figures, as it is nearly the same size as standard LEGO hats. This also means the top of Teemo's head should be designed to fit with other LEGO headgear.

For production, pad printing would work for the glasses and possibly the ears when applied from the front. However, the headband could only be pad printed from the top, if at all. Overmolding the headband seems like the most viable solution.

I'm also pleased that I managed to recreate the fluffy cheeks without introducing undercuts.

Momo (Avatar)

Organic shapes

Process: Injection molding with one slider

Momo's big ears and rounded shapes did not lend themselves to the blocky aesthetic of LEGO animals. This allowed me to finally create a more organic piece. However, this complex shape could only be achieved using a core-cavity combination from the front and back. At this scale, there are no clever solutions for adding a hole for studs, so a slider is required for this specific task.

The face and ears can easily be pad printed. The tail on the back, however, could be left white—but this would surely upset some of the more passionate fans of the TV show.

This is not the only LEGO Momo at minifigure scale. However, the official version is widely considered—by many, myself included—to be one of LEGO's worst creations.

Stud Reversal

On my personal wishlist

Process: 2x Basic (no side actions)

Most LEGO builders eventually find themselves wanting to reverse studs, but the current solutions require far too much space!

Reversing studs within a single plate is not possible due to the LEGO logo on the studs. However, this issue can be avoided by making the piece half a stud taller. This adjustment would still fit within the LEGO system, thanks to elements like headlight bricks and brackets.

For a unique brick intended for frequent use, I prefer to keep one rounded edge. This allows builders to decide whether they want the rounded edge facing outward.
(A half-rounded solution would create ugly gaps.)