Anticonsumption

Ask them to donate to MSF Gaza

I had people contribute to my honeymoon. More personal and fun than cash, still wedding-related, people liked the pictures.

Ask them to "buy" you a few hectares of rainforest somewhere so that you can protect it from deforestation (and then either live there yourself and send someone there to protect it from deforestation).

It's your wedding. If you want money because you have everything you need, put that on the invitations. If someone doesn't want to do that, their problem.

When my wife and I got married, we asked for no gifts and instead provided a list of non-profits (focused on advocating for marriage equality) that we invited guests to donate to in our name.

Other things you can do to limit consumption at your wedding: Our church was partnered with a men's shelter, and residents at the shelter were the ones getting paid to set up the space and then rearrange it for the reception while we were outside taking pictures. All the leftovers from the reception buffet went immediately next door to the shelter as well. I don't know how practical the first will be for you, but making sure the extra food (and flowers, if any) get donated is a great way to offset the consumptive footprint of a traditional wedding.

Just be aware that no matter what you say, a few people will still buy you pointless BS because they’re incapable of following instructions. But it’s still worthwhile to discourage it as much as you can.

Jewelry, because you can sell it and its small, so you can also easily store it. But be aware that jewelry costs usually more in stores than you can later sell it for.

Oh yeah, and maybe swords and javelins, because you can decorate your walls with them, cut stuff and also defend your partner from burglars, should the need arise... and you can sell them as well.