Has a 50% chance to mimic the effect of a random passive item from the current room’s item pool when entering a room.
Modeling Clay can only mimic items that have the "summonable" item tag, the same way Lemegeton selects the wisps it summons.
The item given by Modeling Clay is not locked within any given room; constantly leaving and re-entering a room will cause it to cycle between different items.
Items that would give or remove consumables or heart containers will not do so if Modeling Clay mimics them.
If Isaac holds multiple copies of Modeling Clay, they will all mimic the same item.
Note: This will not give multiple copies of the item, Isaac will only receive one copy.
Chaos: Removes the room pool constraint for Modeling Clay's available items.
Sacrificial Altar: If Modeling Clay is currently mimicking a viable familiar, it will also be sacrificed and spawn an additional Devil Room item, but Modeling Clay will not be destroyed.
TMTRAINER: Modeling Clay cannot copy glitched items; it will do nothing and not have a sprite if it tries to.
If Modeling Clay mimics the following items, they will behave in the following ways:
9 Volt: 1-room charge active items will not recharge over time. Other active items are affected normally.
Belly Button / Mom's Purse: Allows Isaac to hold another trinket alongside Modeling Clay if he picks it up while Modeling Clay mimics the item, and he will continue to hold both even after Modeling Clay changes. If Isaac tries to pick up another trinket while he already has two, it will instead be destroyed and he will only be able to hold one trinket again.
Isaac can safely exchange cards/pills/trinkets by manually dropping them, at the cost of being unable to hold two.
Extra trinkets held this way are susceptible to not working properly, if at all.
Little Baggy / Polydactyly / Starter Deck: Allows Isaac to hold two cards and/or pills if he picks them up while Modeling Clay mimics the item, and he will continue to hold both even after Modeling Clay changes. If Isaac tries to pick up another card/pill after Modeling Clay changes, the inactive card/pill he was holding will be destroyed and he will only be able to hold one card/pill again.
If Isaac goes to a new room while Modeling Clay mimics Starter Deck/Little Baggy, cards/pills in the new room will be converted appropriately.
Rock Bottom: Permanently increases Isaac's stats when it transforms into an item that surpasses Isaac's current stats.
This allows the player to enter and exit a room any number of times in order to get as many stats as possible.
Because Modeling Clay can constantly cycle between items by constantly exiting and re-entering rooms, many items’ effects can be forced with enough patience to get maximum value out of the trinket. Aside from the interactions listed above, the following items/effects can be forced in order to gain value from the trinket in the following ways:
Explosive shots: Allows Isaac to destroy rocks and open Secret Room doors without spending resources.
Hallowed Ground can be used first to spawn a white poop next to a Machine/Beggar that takes health to give Isaac the chance to resist damage taken from using them.
The Battery: Allows Isaac's active item to be overcharged; overcharging will persist after Modeling Clay changes.
Cancer / The Wafer: Reduces the damage taken from Sacrifice Rooms to half a heart, allowing Isaac to use them more.
Echo Chamber: Cards and runes’ effects will be stacked if used while it mimics the item. The game will remember what cards and runes were used if it turns into Echo Chamber in the future, even on later floors.
Scapular: To gain a soul heart if at low health. This will not work if the damage source is considered "health donation", such as from a Blood Donation Machine, Demon Beggar, Confessional, or Hell Game, but it will work for Curse Rooms and Sacrifice Rooms.
Sharp Plug: Isaac’s active item can be instantly recharged at the cost of red hearts.
The trinket's icon appears to be a clay model of Meat Boy from Super Meat Boy, another game by Edmund McMillen.
The item is a direct reference to the item of the same name in The Binding of Isaac: Four Souls, which turns into another available item when used.
Walking between rooms back and forward with Modeling Clay may cause the game to crash at random.
Normally, Modeling Clay's appearance changes to reflect what item it's imitating. This is not the case if the trinket is absorbed, e.g. through Smelter. It will appear in the Found HUD where passive items appear, like other absorbed trinkets, but will never change its appearance.