Random #ThingUmbrella tip & tidbit about unit conversions: I've been sourcing materials for a larger contact printing setup for my kallitype process, incl. getting a much heavier ultra-clear glass plate than what I've been using so far.

Using the https://thi.ng/units converter with its Lisp-like domain specific language, I can easily compute the following, freely mixing compatible units with complete ease. Using the S-expression DSL is optional. There's also a normal TypeScript/JavaScript API...

```
// weight in kilograms of 48cm x 35cm x 8mm plate
(kg (* 48cm 35cm 8mm glass))
// 3.36

// or use a DIN paper size preset
(kg (* (area din_a3) 8mm glass))
// 2.4948

// calculate force
(newton (* 48cm 35cm 8mm glass earth_gravity))
32.86191

// calculate PSI (pounds per square inch) of the plate on a smaller area
// here for a 6x4" print area example
(psi (/ (* 48cm 35cm 8mm glass earth_gravity) (* 6in 4in)))
// 0.30782

// compare with a simple picture frame
(psi (/ (* 24cm 30cm 2mm glass earth_gravity) (* 6in 4in)))
// 0.03298

// ...the thicker plate causes ~10x more pressure. q.e.d.
```

Maybe someone else finds that useful. The package readme contains a lot more information about possibilities, predefined constants and examples...

#ThingUmbrella #UnitConversion #Physics #TypeScript #JavaScript #DSL #Lisp