Put a musician-wanted ad in the local music paper. Write a brief description of the type of music that you are striving for -- listing musical influences helps clarify your goals and aspirations. List the types of instruments you are searching for, such as upright bass, mandolin, washboard and so forth. Provide a name and contact information.
Play open-mike nights at local venues. Put together a few songs, originals or covers, and raise your profile and visibility by playing at open mikes. This is a good way to meet like-minded musicians. Search for clubs and night spots that are sensitive to the folk punk aesthetic.
Put up fliers in local coffeehouses and record stores advertising for musicians. Record stores and coffeehouses are also good places to search for musicians who are into the folk punk genre. Make your flier eye-appealing and attention-grabbing. Cynicism and humor are common themes in folk punk music. A well-constructed flier gives potential bandmates a glimpse into your personality and tastes.