Building Block Bath Bomb with Car Inside, Block Bath Bomb, Bath Bomb, Kids Bath Bomb, Boy Bath Bomb Building Brick shaped bath bomb scented in Blue Raspberry Slushy. Full size Hot Wheels Car in each one. All bath bombs are hand pressed and hand painted. There may be some imperfections or cracks do to the handmade nature, These imperfections will not have any effect on the function of bath bomb. Bath bombs are single-use, blends of smoothing, fragrant extracts and oils that you can toss in your tub before bath time. The primary ingredients are sodium bicarbonate and citric acid, which interact with each other once dissolved in water to create that fizzing effect we know and love. Once this reaction occurs, the bath bomb dissolves and breaks apart, releasing all the good stuff inside: from delicious scents to skin smoothing emollients, which act as softeners on your skin.