How can you build a model of tetrahedral coordination from objects found at home?
Inflate balloons, and tie them «at their stem» like a bouquet of flowers.  If you take four of them, not too much inflated, you well demonstrate a situation close to $sp^3$ hybridization. These models equally work well in larger lecture halls by the way, and intentionally using different colors allows many options.



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You need some worked examples?  See videos like this or this.

You need a scientific paper? Well, there are as well, e.g., this (open access) expanding the picture to extended $\pi$-systems: