In chemistry there are several variables that have clear trends across and down the periodic table such as:
electronegativity, electron affinity, ionization energy, atomic radius, and ionic radius
To help student visualize the trends, it would be great to have a 3D physical model that is twenty squares for the first twenty elements with the element symbol on top and the name of the height of the block determined by the relative magnitude of the value for the variable for that element.
With my own 3D printer I can make one for each lab group to examine and compare, and expand to make a larger model that includes the transition metals as well.
To make the models, I can use Sketch Up. For a model of a periodic trend like atomic radius here are the steps:
Look up the values for the atomic radius of each of the elements.
Draw a square for each of the elements.
Use the push-pull tool to raise the height of each square by the correct relative height.
This will make a simple block style model, depending on how the final product looks I can add an indented element symbol to the top of each rectangle and an indented label on the bottom of the model to indicate that it is a model for atomic radius. I can also print in with different colors for metals, nonmetals, and metalloids.