We love non-standard conductive materials here at Adafruit, and now we have a metal-based conductive paint for your crafting needs. This silver/tin/copper based conductive paint is usually used to repair flex circuits or maybe fill in gaps in EMF shielding. But you can use it on paper, plastic, fabric, etc. to create a low-resistance conductive connection.
The Chipquik Conductive Paint 5cc Syringe provides low resistance, metal-based conductive paint in 5g syringe with a plunger & two tips. It can be applied by dispensing, paint brush, or with stencil and squeegee.
Compared to carbon-based conductive paints like Bare Conductive, metal-based paints have lower resistance so you can pass more current through them. They also tend to crack less when bent or flexed. But, they are more expensive.