Cable release mod

There are a couple of ways to fit your Holga with a cable release. You can either glue something onto your Holga that a cable release can fit into, or you can buy attachments that fit over your Holga from eBay:

Cable Release Mod Cable Release
mr_phillip's cable release socket
made from a nut from a old Mac
A cable release mod
I bought from eBay
 

I'm afraid you are on your own finding a suitable nut to glue onto your Holga! BURNBLUE came up with a pretty sweet non-destructive method using a clamp:

Clamp Release
BURNBLUE's cable release clamp