(Name could probably be improved)

Cards which interact in interesting ways with cards with the same mechanics has been something of a Gearsmith theme. Examples: Nodes, Kaisers, Horsemajigs. Let's start with an example....

Basic Mergemajig
1 [E]
Gearsmith Character - mergemajig

If this is a 'gear' card, attached character gains 1 strength and 1 life.

COST: Use only if this is a character. Pay 1. Pick a 'Mergemajig' character.
EFFECT: This card becomes a 'gear' item. It's no longer a character. Attach it and all attached Mergemajigs to the picked character.

COST: Use only if this is a 'gear'. Pay 1.
EFFECT: Detach this card. It becomes a character and is no longer an item.

Mergemajigs can be either characters or gear for other Mergemajigs. They start off as characters. As gear, they pump the attached Mergemajig by their strength and live. If they don't have 3 speed, they also grant the difference from 3 in speed. So a 4-speed would grant 1 speed and a 1 speed would grant -2 speed. It also grants any non-Mergemajigs rules text. So if a Mergemajig had the can-attack-turn-it's-played effect, it would grant this as a gear.

They always have an ATTACH ability. The cost may vary from card to card. Note the wording: if I attach A to B and then B to C, A moves from B to C. The wording of the attack ability might be better with some timing restriction, like HANDOFF. Or maybe not.

The DETACH ability returns it to being a character. Some Mergemajigs may not have this ability.