Making Lab Equipment
Chemistry experiments require some basic lab equipment, most of which can be easily made from materials found in the home. Better yet, with 3D printers it is easy to make custom equipment that would have been prohibitively expensive for use in the home.
Stands & Racks
Wire test tube stands
The Golden Book of Chemistry Experiments contains a useful section of making chemistry lab equipment. Among the described equipment are plans for these wire test tube holders. Using a soft beading wire they are easy enough for a 8-9 year old scientist to make with minimal supervision, while still being useful enough to actually get used and be useful in experiments.
Test tube rack
This is a simple box frame test tube holder. It is fast and easy to make, yet really cleans up the chemistry bench and makes any experiment involving test tubes much easier to pull off. I suggest added a hole to hold a small glass funnel for loading the test tubes.
Equipment
Printed test tube ice bath holder
For experiments where you want a hot vapor to condense down into a liquid most chemistry set books just show jamming a test tube down into a water bath with some ice. The problem with that approach is that when the ice starts to melt there is nothing really supporting the test tube. While it works, that unsuported test tube is a problem for a lot of reasons. This 3D printed jig supports the test tube in a standard 250ml beaker, and in the same position, even as the ice melts.
Dual test tube electrolysis jig
This printed rack takes care of running the electrode wires internally, and holds two 25mm test tubes inverted over a standard 250ml beaker. There is a cross bar lock to secure the test tubes in place while carrying. In retrospect this design is solid, but it needs to be remade to use a larger beaker for easier loading and unloading of the test tubes once they are filed with fluid.