Solid Foundations is a framework which allows for custom buildings in Stardew Valley.

Solid Foundations introduces many features for custom buildings:

Dynamic, animation-supported texture overlays, with optional conditions
Custom interiors
Item production via user-defined rules
Building skin variation
Custom material cost and build rules
Custom exterior collision
Dynamic "touch" and "walk" player actions (such as warping when player walks on a tile)
...and much more!

See the GitHub repository for an in-depth wiki on how to create a content pack for Solid Foundations.

See the example pack in the Optional Files section for an example custom buildings pack.
See Mystical Buildings for an SF pack which utilizes Solid Foundation's API.

Content Patcher is supported!

Dynamic Game Assets is supported!

Save Anywhere is supported!

To use this framework, you need a Solid Foundations content pack.
These content packs will add the custom buildings to either Robin's or the Wizard's construction menu.

Removing downloaded SF packs will result in their respective building disappearing from your map, with no other impact on your save file.

For a general example pack, see the mod's repository.

For a pack which uses Solid Foundation and Content Patcher (as well as Solid Foundation's API), see the Mystical Buildings pack.

Can I uninstall Solid Foundation without issue?

Yes, though any placed custom buildings will disappear. Re-installing Solid Foundations will result in your custom buildings being restored.

Can I uninstall Solid Foundation content packs without issue?

Yes, though the respective custom buildings will disappear. If you re-install the SF content pack before saving, the custom buildings will be restored. Otherwise they will be lost.

What are the limitations?

See here for the current list of unsupported features.

Source code is available here.