Multiplication puzzle generator

This is based on [Puzzle generator](https://www.thingiverse.com/thing:1427568). It places a multiplication table on a puzzle. The piece's height, as the number shown, is in millimeter.

Parameters:
- `piece_side_length`
- `same_side`
- `n`
- `spacing`

Basically, the `n` parameter may be any positive value, but I restrict it from 1 to 9 in the Customizer because I don't want the number too small. The number size is `piece_side_length / 3` is the .scad file.

If you want to generate a multiplication puzzle with a `n` bigger than 9. Download the .scad file and modify the `size` parameter of the `text` in the `puzzle_piece_with_text` module.

Find all my puzzles in [puzzles collection](http://www.thingiverse.com/JustinSDK/collections/puzzles).


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- *[OpenSCAD Documentation - Traditional Chinese](http://openhome.cc/Gossip/OpenSCAD/)*
- *[OpenSCAD Documentation - English](http://openhome.cc/eGossip/OpenSCAD/)*

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