What is a synonym for the word contraption?

Here are some synonyms for "contraption," depending on the context and nuance you want to convey:

Neutral:

* Device

* Gadget

* Mechanism

* Apparatus

* Machine

* Tool

Informal:

* Thingamajig

* Doohickey

* Gizmo

* Whatchamacallit

* Doodad

Negative connotations:

* Rube Goldberg machine

* Frankensteinian

* Clumsy

* Incompetent

* Unwieldy

Positive connotations:

* Ingenious

* Innovative

* Clever

* Resourceful

The best synonym will depend on the specific context of your writing.