A free mod for Stardew Valley, by aedenthorn.

Custom Decoration Areas (Custom Walls and Floors) is a mod that adds several new decorations to the game, allowing players to customize the look of their houses and other buildings with custom walls and floors. It can be used with decoratable locations (FarmHouse and Shed), as well as ordinary game locations, including the following vanilla locations:

JoshHouse

HaleyHouse

SamHouse

Blacksmith

Saloon

Trailer

Hospital

HarveyRoom

ElliottHouse

ScienceHouse

SebastianRoom

Tent

AnimalShop

LeahHouse

SandyHouse

WitchSwamp

WitchHut

WitchWarpCave

BathHouse_Entry

BathHouse_MensLocker

BathHouse_WomensLocker

Greenhouse

SkullCave

Backwoods

Tunnel

Trailer_big

Sunroom

LeoTreeHouse

Custom Decoration Areas (Custom Walls and Floors) is a framework that allows mod authors to create content packs that either add / replace flooring and wallpapering rectangles to compatible game locations.