Piano covers were a popular Victorian household item, that you could either buy or make at home. Ideally, they were covered with lavish embroidery, the creating of which would occupy the young ladies of the house for all the hours that they were not actually practicing the piano. These became very fashionable in the 1880s and 1890s.
In 1885, Arthur's Home Magazine described a "handsome and not very expensive" piano cover that you could make out of dark red cloth with a border of black velvet ribbon "with fancy stitches done in bright gold" silk thread. The illustration from Arthur's is above right, showing what you'd be aiming for. At the edges were "fancy ornament[s] of gold and red, thus forming a handsome and rich-looking fringe." The writer added that you could use tassels made over from old fringes, but if you were really refined you would stick to the theme of the pattern, which was, most emphatically, fancy. The piano cover shown below, on the left, is from St. Mark's Church in London, a modern take on the embroidered Victorian cover.
If you preferred painting to embroidering, you could decorate your piano cover accordingly. A lady wrote to Ingall's Home and Art Magazine in 1889, asking how to paint a flowered border on a piano cover: what material could she paint on without the paint running? And what colors should she use? The answer was to use velvet or felt in "terra cotta or subdued red, dark olive or electric blue." And as long as she didn't get too enthusiastic and use too much paint, it probably wouldn't run.
You can still buy piano covers today, although they tend not to be velvet with painted flowers or dangling fancy ornaments. As ever, they keep dust and sunlight from damaging the piano, which will make any piano restoration jobs easier by preserving the instrument as much as possible when not in use.