This project uses OpenScad which is a 3D Solid modeler for 3D printing. OpenScad has the advantage that it's a programming language too, which lends itself to heavy customization. You can customize everything, and if you don't like it or need something else, then change it.
Helmholtz Coil Configuration Statistics:Output in the OpenScad console details the coil configuration, wire length, field strength per Amp / mA and the maximum capacity of the coil:
AWG: 30 Coil Diameter: 21cm Coil Turns: 3 25649.22370 nT / 0.25649 Gauss per amp 25.649224 nT per mA Wire length per coil: 1.98m Combined resistance of both coils: 0.001342Ohms Voltage required to drive coil: 0.00026979Volts @ 0.201Amps Maximum magnetic coil capacity: 5155.49396nT for the provded gauge Usable Volume (Cylinder): 105Length(mm) x 70Diameter(mm)
The inner cylinder of the coils (the space that is 1/3 the diameter of coil), denotes the area of uniform magnetic field.
The platform for magnetic experiments is replaceable, so you can switch platforms for different applications.
This device was designed for testing magnetometer coils in the Aurora Observatory project.
It's easy to build multiple coils, e.g. I require one strong enough to null Earth's field, but also require one that is sensitive enough for measuring 1nT changes in the Earth's field.
Here is a slideshow I've put together on how to measure the Earth's magnetic field using this Helmholtz Coil design: