Materials
Dulux paints, two different colours
Undercoat paint
Sanding paper
MDF board
Liquid nails
No more gap filler
Old bookcase
Tools
Jigsaw
Paintbrushes, small and big one
Touch-up paint brush
Quick-grip bar clamps
Steps
Step 1

I saved old bookshelf going to landfill, because I needed a one to my daughter's room.
First I sanded lightly, wiped it down, applied no gap fillers to the shelves and painted undercoat.
Step 2
I then measured right size of MDF board that I already had handy, and I designed arch to be cutted. I cutted the arch with jigsaw.
I sanded the arch so the edges wouldn't be too sharp.
Step 3
Then I went back to painting. I painted the bookshelf with this beautiful orangish/ pinkish colour plus added yellow strips to the back of the bookshelf. I painted it twice.
Step 4
When the paint was dried completely I glued the arch onto the top of the top shelf with liquid nails. I attached bar clamps to hold the arch so it would not slide down while drying.
Step 5
When the arch was secured and liguid nails dried. I applied no gap filler to the edges of the MDF board and let it dry. I sanded the bottom parts of the arch + excess filler off so the surface would be smooth. Then I wiped it down, and painted the arch to match to the rest of the bookcase.
