Here's a very rough conversion of the manikin from the 2E Mystara MC.
Manikin
Diminutive Construct
Hit Dice: ½ d10 (3 hp)
Initiative: +3 (Dex)
Speed: 30 ft.
AC: 17 (+3 Dex, +4 size)
Attacks: -
Damage: -
Face/Reach: 1 ft by 1 ft/0 ft
Special Attacks: Shriek
Special Qualities: Construct, Bond, Tether
Saves: Fort +0, Ref +3, Will +0
Abilities: Str 6, Dex 17, Con -, Int 3, Wis 11, Cha 12
Skills: Hide +21*, Move Silently +9*
Climate/Terrain: Any temperate land and underground
Organization: Solitary
Challenge Rating: ½
Treasure: None
Alignment: Always Neutral
Advancement: None
A manikin is a small, plant-like construct built by wizards to aid in their laboratory work. Made from a rare plant called mandragora, the manikin has a vaguely humanoid body structure resembling that of a root.
Combat
A manikin avoids combat if at all possible, using its stealthy abilities to remain unnoticed. It is defenseless, save for its death shriek it strikes down its killer with.
Shriek (Su): Whoever lands the killing blow on a manikin must make a Will Save (DC 11) or be struck dead. Even those not able to hear the shriek are not protected from this attack.
Construct: Immune to mind-influencing effects, poison, disease, and similar effects. Not subject to critical hits, sub-dual damage, ability damage, energy drain, or death from massive damage.
Bond (Ex): A manikin has an innate bond and telepathic link with its creator. When a manikin aids its creator in doing research or crafting magical items, it gives its master a +1 circumstance bonus per manikin used on all related checks, up to a maximum of +4. If a manikin is killed, the master suffers all the effects she would as if she lost a familiar (see the PHB). Once the creator dies, all of her manikins perish as well.
Tether (Ex): A manikin is linked to an immovable point which serves as its tether. It cannot move more than 100 ft away from this focal point. In addition, a manikin must be in soil for at least one hour per day and receive the necessary nutrtition (sunlight and water) a normal plant would need each day. A manikin unable to meet these requirements loses one hit point per day its needs are denied.
Skills: *A manikin receives a +6 racial bonus on Hide and Move Silently checks.
Crafting a manikin
To create a manikin, a would-be creator must have the Craft Wondrous Item feat. Crafting one consumes 100 gp worth of material and requires the root of the rare mandragora root. Crafting one requires a successful Profession: Herbalist check (DC 13) and drains the creator 25 experience points. The creator must choose a spot or object a manikin is bound to; this can never change.
Harvesting a mandragora root is dangerous. The creature who pulls the root out of the ground is subject to a shriek attack exactly the same as the manikin’s death shriek. Removing the root with a rope is not enough to escape its wrath. Evil and cruel wizards are known to use animals to remove the root, thus avoiding having to make a save. Practical wizards often remove the root using an unseen servant spell.