Update README.md

README.md

@@ -1,8 +1,6 @@
 # Gridfinity Rebuilt in OpenSCAD 
 
-A ground-up port (with a few extra features) of the stock gridfinity bins in OpenSCAD. Open to feedback, because I could not feasibly test all combinations of bins, so some of them may have issues. I tried my best to exactly match the original gridfinity dimensions, but some of the geometry is slightly incorrect (mainly fillets). However, I think they are negligible differences, and will not appear in the printed model. 
-
-[Gridfinity](https://www.youtube.com/watch?v=ra_9zU-mnl8) by [Zack Freedman](https://www.youtube.com/c/ZackFreedman/about)
+A ground-up port (with a few extra features) of the stock [gridfinity](https://www.youtube.com/watch?v=ra_9zU-mnl8) bins in OpenSCAD. Open to feedback, because I could not feasibly test all combinations of bins. I tried my best to exactly match the original gridfinity dimensions, but some of the geometry is slightly incorrect (mainly fillets). However, I think they are negligible differences, and will not appear in the printed model. 
 
 ## Features
 
@@ -11,22 +9,47 @@ A ground-up port (with a few extra features) of the stock gridfinity bins in Ope
 [<img src="./images/height_dimension.gif" width="320">]()
 [<img src="./images/tab_dimension.gif" width="320">]()
 [<img src="./images/holes_dimension.gif" width="320">]()
+[<img src="./images/custom_dimension.gif" width="320">]()
 
 - any size of bin (width/length/height)
 - any number of compartments (along both X and Y axis)
 - togglable scoop
 - togglable tabs, split tabs, and tab alignment
 - togglable holes (with togglable supportless printing hole structures)
+- manual compartment construction (make the most wacky bins imaginable)
 
 [<img src="./images/slicer_holes.png" height="200">]()
 [<img src="./images/slicer_holes_top.png" height="200">]()
 
 The printable holes allow your slicer to bridge the gap (using the technique shown [here](https://www.youtube.com/watch?v=W8FbHTcB05w)) so that supports are not needed.
 
+## Instructions
 
-## Recomendations
+Set the values for `gridx`, `gridy`, and `gridz` global variables as the overall size of the bin. The stock bins have a `gridz` of either 2, 3, or 6. 
+
+The function `gridfinityEqual(n_divx, n_divy, style_tab, enable_scoop)` is provided to allow an easy way to generate the "traditional" bins. `n_divx` and `n_divy` are the number of compartments along X and Y, respectively. `style_tab` determines how the tabs for labels are generated. 
+- 0: full tabs across the entire compartment
+- 1: automatic tabs, meaning left aligned tabs on the left edge, right aligned tabs on right edge, center tabs otherwise
+- 2: left aligned tabs
+- 3: center aligned tabs
+- 4: right aligned tabs
+- 5: no tabs
+
+`enable_scoop` toggles the scoopy bit on the bottom edge that allows easy removal of items. 
+
+If you want to get crazy with it, you can take control of your destiny and manually place the compartments. This can be done using the `gridfinityCustom()` function, which will cut all child objects into the container. There are various modules that are exposed for this purpose. 
+
+`cut(x,y,w,h,t,s)` will cut a compartment at position `(x,y)` that has a width `w` and a height `h`, along with a tab alignment `t` and togglable scoop `s`. The coordinate system for compartments originates at the bottom left corner of the bin, where 1 unit is the length of 1 base (42mm by default). Positive X and positive Y are in the same direction as the global coordinate system. The tab style and scoop only apply to the specific compartment. `(x,y,w,h)` do not have to be integers. For example, in a 3x3 bin, `cut(1,1,1,1,0,true)` would cut a 1x1 compartment in the middle of the bin with a full tab and a scoop. 
+
+`cut_move(x,y,w,h)` will move all of its children from the origin to the center of the area that a compartment would normally fill, and cut the block. This allows you to easily make custom cutouts in the bin. For example, in a 3x3 bin, `cut_move(0,0,3,1) cylinder(r=10, h=100, center=true);` would cut a circular hole of radius 10 in the bottom center block of the bin. 
+
+Examples can be found at the end of the file (they were used to generate the last gif). 
+
+## Recommendations
 For best results, use a version of OpenSCAD with the fast-csg feature. As of writing, this feature is only implemented in the [development snapshots](https://openscad.org/downloads.html). To enable the feature, go to Edit > Preferences > Features > fast-csg. On my computer, this sped up rendering from 10 minutes down to a couple of seconds, even for comically large bins.  
 
 ## Enjoy!
 
 [<img src="./images/spin.gif" width="160">]()
+
+[Gridfinity](https://www.youtube.com/watch?v=ra_9zU-mnl8) by [Zack Freedman](https://www.youtube.com/c/ZackFreedman/about)