I came across a mat on Amazon.jp that is designed for tummy time. It's the first time I've see a product on there advertised for that purpose. The mat we have came from the US since I couldn't find one in Japan 3 years ago.
Here are some ideas of activites for tummy time:3 months old - mat near the window, plastic mirror, books, ring stacking toy - all within reach
3 months old - mirror, ring stacker, baby doll, cloth books, gauze, window
4 months old - grapefruit, apple
tummy time outside
5 months old - balls, towel for hiding toys, stacking cups
Any baby toys can be put just within reach to encourage exploration. Other carefully chosen household products are great too. A plastic cooking spoon, small cloth bag, citrus fruit, colorful placemats... things that seem ordinary to us are often the most interesting to babies!
Of course tummy time should always be closely supervised but not over supervised. Put on some nice music and give the babe a chance to explore while you sit back and quietly observe! You may learn a thing or two too!
* Please keep in mind that tummy time is for play time. Babies should be put to sleep on their backs!