Free contributions are attached to wishlists rather than wishlist items. To make a free contribution to a wishlist first make sure that the free contributions module is enabled by the store administrator in the crowdfund settings in the backend.
Then also make sure that the free contributions module is enabled for the specific wishlist that wants to receive free contributions. This can be done by the store administrator in the backend or by the wishlist owner himself in the frontend.
If the store administrator has not enabled free contributions globally in the crowdfund settings, the module cannot be enabled for individual wishlists.
Free contributions have to be enabled for individual wishlists because not all wishlist owners may want to receive free contributions for their wishlist.
Once the free contribution module is enabled for a wishlist, in the single wishlist page where wishlist items are added to the cart there would be a separate form for adding the free contribution to the wishlist, as shown below.
As usual, the position and elements of this form can be customized to suit the stores needs.
To make a free contribution, all the customer needs to do is to enter the contribution amount and click the “Contribute” button.