In making art you sometimes meet problems which are difficult to solve by trial and error. An example is my own work about dividing a sphere in two congruent halves (Sphere in 2 parts).The idea that there should be interesting ways of dividing is a first step. Depending on your imaginative faculties you can make a plan for such a division. But realizing this is a very accurate job and some mathematical calculation and drawing is of great help.

I have been able for several times helping artists and designers in solving this kind of problems. I like that and it inspires me. I ask for working on a problem, when talking about a problem or by solving math problems that arise 25 euro/hour. There are always some less interesting things to do when the real work is done: traveling time, describing solutions, making an Excel sheet for exploring possibilities for the artist himself, writing a computer program for making a special drawing… For that part of the work I also ask 25 euro/hour. This means that I also don’t ask any money (except for traveling expenses), whenever I can’t solve the problem.

**Some examples of projects:**

**Distorted squares**. For a presentation of photographs I was asked to design an object in 3D with in top and on the bottom a square, the first smaller than the second, with corners exactly above the sides of the bottom part. The idea was to make a simple paper folded model for this. There should be in advance the possibility of comparing different solutions, in order to make a good decision for the final object. This project was finished with satisfaction for both persons concerned. The reliefs I made with “distorted triangles” are a spin-off of this project. Total time spent: 7 hours.

**Sphere lamp**. I was contacted by a designer who wanted to make a large lamp made of small industrial lamp-shades in the shape of knotted cones. It was a nice calculating problem and my solution satisfied. I myself was at that time working on the platonic solids made of anti-prisms. The calculations I did for the lamp were very useful for the problems with the platonic solids. Total time 6 hours

**Drawings for a book about the kinetics of Laban**. I was asked if it was possible to make drawings of some specific solids, all fitting into the same sphere. And all of them in the same orientation. It was necessary for didactical reasons to present drawings in a variety of orientations in order to choose the best for the purpose of the book. There were still some other detailed demands. The program I wrote for making all these drawings in different orientations was quit a job. A designer helped to make the final drawings really sophisticated. Totoal time for this project: 12 hours.