1 The new tool should be cheaper than the one it replaces.

2 It should be at least as small in scale as the one it replaces.

3 It should do work that is clearly and demon-strably better than the one it replaces.

4 It should use less energy than the one it replaces.

5 If possible, it should use some form of solar energy, such as that of the body.

6 It sh

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