The Knives and bottles table

[BMAD]

You need to visualize three soda bottles with narrow necks and four table knives. Place the three bottles on a flat surface so that each bottle forms the corner of a triangle. The distance between the bases of any two bottles should be slightly more than the length of a knife.

 

Using no more than these materials construct a platform on top of the three bottles. No part of any knife may touch the ground. The platform must be strong enough to support a full glass of water.

[bonanova]

Maybe just three knives would work.

 

The tips of the handles of the knives rest on the bottlenecks.
The blades interleave at the center of the triangle.
Each blade passes under the first, and above the second of the other two knives.
The blade tip of each knife rests on a blade of another knife, supporting the weight of the water.

So I wonder how to utilize a fourth knife..

[bonanova]

The distance between the bases of any two bottles should be slightly more than the length of a knife.

 

Is the distance center to center or edge to edge?

I'm assuming edge to edge, which makes a better puzzle, but not certain.

[BMAD]

 

The distance between the bases of any two bottles should be slightly more than the length of a knife.

 

Is the distance center to center or edge to edge?

I'm assuming edge to edge, which makes a better puzzle, but not certain.

 

I am unsure by what you mean but the bottles are the vertices of the triangle and the edges are slightly longer than the knife length (the knifes are congruent)

[BMAD]

The fourth knife is a distraction.  hold it maybe as the rest balances the water.