My synagogue, like many (most?), gets only a portion of its annual income from member dues and investment income, with the rest coming from various fundraising activities. Most of this fundraising targets our own members. Some members have both the means and the inclination to contribute to endowments or other funds, which is great, but they can't do it all.
So what about external sources of donations? I asked our board about grants (not knowing much about grant-writing myself, but having heard it's a thing) and was told that's not viable, but I haven't pressed for details yet. (We did get a recent government grant to improve security, but this was described to me as exceptional.) Some non-profits get corporate donations and we get some of that in the form of ads in tribute books, but that seems to be less common for religious institutions (and it's not clear to me what they get from it if they don't get their name on a building or some such). We've sometimes had public events like food festivals that are designed to raise money, but they haven't raised a lot and they cost a lot of volunteer labor. (Maybe we're not choosing the right ones.)
What do other synagogues do? How do you raise external funds? I'm interested in answers that address both short-term income that balances the annual budget and long-term income that helps build an endowment.
(Because I use my real name online and that makes it fairly easy to identify my congregation, let me note here that we are not in any immediate danger or anything like that. This is about long-term planning so we don't get into trouble.)