updating the docs

documentation/build_docs.md

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+# how to build r_e_c_u_r
+
+## get some parts
+
+these are the parts you need to get. to reduce costs i sourced them through aliexpress.com but if you have other parts lying around try them out and let me know how it goes.
+
+### main parts:
+
+- [raspberry pi3] *37 USD* (watch this space for experiments with other models/sbc's)
+
+![alt text][raspberry pi image]
+
+- [raspberry pi screen] *12 USD*
+
+- [usb keypad] *9 USD*
+
+other bits and pieces:
+
+- xxx and yyy size screws and nuts - a few dollars (exact sizes, links etc coming soon)
+
+- >=8 gig mircoSD card
+
+- stable 5volt1A microUsb power supply
+
+- a usb for samples
+
+- hdmi cable for output...
+
+## print some things
+
+- 3d print the front panel, back panel and spaces from these files
+
+- 2d print the key mapping (or modify/create your own!) from here onto label paper or something sticky...
+
+## put it together
+
+- using etcher (or otherwise) flash the micro sd with this modified image of raspberian (or follow the dotfile instructions here)
+
+- insert sd card into pi
+
+- attach screen via the pi header pins and use screen spacers (with a little bluetac) to fasten it in
+
+- use the small screws to attach pi+screen to the back panel
+
+- attach keypad to the back panel and fasten in with a extra screw if nessicary
+
+- put large screws through back panel facing up and use spacers
+
+- attach top panel and hold with nuts
+
+## try it owt
+
+[raspberry pi3]:https://www.aliexpress.com/item/RS-Version-2016-New-Raspberry-Pi-3-Model-B-Board-1GB-LPDDR2-BCM2837-Quad-Core-Ras/32789942633.html?spm=a2g0s.9042311.0.0.FkRWty
+[raspberry pi image]: ./images/build_01_pi.jpg
+[raspberry pi screen]:https://www.aliexpress.com/item/New-3-5-inch-Raspberry-Pi-LCD-TFT-Touchscreen-Display-Touch-Shield-Raspberry-pi-2-Model/32605410449.html?spm=a2g0s.9042311.0.0.ZW1WDU
+[usb keypad]:https://www.aliexpress.com/item/2-4G-Wireless-Keyboard-USB-Numeric-Keypad-19-Keys-Mini-Digital-Keyboard-Ultra-Slim-Number-Pad/32818206308.html?spm=a2g0s.9042311.0.0.FkRWty