I stick to 180mah 2S LiPos (Turnigy Nanotech) and even in my higher powered robots I can get at least 10 minutes running out of them.
3D printers are bad at threads. I use M2 screws to hold everything onto a 3D printed chassis that doesn't get bolted on with a seperate metal nut. "1) 3D printers aren't great at threads. We just put holes which are slightly smaller than the threaded end of the screw and then drill the screw in after it has printed. Never had any cracking providing that the screw holes are encased inside a square section and are bulked out around the edges." Good advice right here!
LED's I just order off of ebay, can get a pack of 20 for £2 with free postage if you hunt around a bit. You just need to wire the LED using the +ve and -ve of the receiver with a resistor in line somewhere. The order doesn't matter as long as the LED is the right way around.
Yeah I just use scissors for 1.5mm polycarb, I wouldn't go thicker as it becomes a pain to work with and 1.5mm is enough.
I always use switches in my bots and you can pick up some nice small ones in maplins like the ones in the link in my signature (seems a waste of postage for one switch though
).
One thing on 3D printing is don't skimp out on bulking the chassis, your armour is only as good as what you bolt it to. I print in ABS for it's nice material strength that has a density of 1g/cm^3 so you can put a lot of plastic into the chassis without worrying about weight.
) which I don't want to start designing until all the parts are here. Hobbyking are currently out of stock of the batteries I ordered so I am not sure when this bot will be done by. A brief description of the idea is a 3D printed frame with polycarbonate panels: similar in concept to Anticide. Possibly to have the top chassis of the bot screw on to a base to allow access to all inside electronics and/or a removable panel (ie screw not glue) near the battery for even easier access. This leads to my first question: how are 3D printers at printing small screw threads? If the answer is bad, what methods do you guys use for attaching screws to 3D printed bots (ie can you print a regular hole and drill a screw in without causing cracking?) or is there a better way to connect things you want to be able to take apart? Also what tools are best to use for cutting polycarbonate? My next question is about ON/OFF switches. Basically, does anyone use them? A switch (perhaps accessible under the flipper?) seems more convenient that having to disconnect the battery each time. Another question to go along with this is how long does a battery charge generally last (im using the 7.4V Turnigy lipo which seems pretty standard). If it's only a couple of matches and the battery has to be disconnected often anyway I'll rethink the design a little to make it easy access and hence I obviously wouldn't really need a switch. My next questions are about the LEDs, I'd like to add some to the bot. Rory briefly explained this to me when I ordered the NanoTwo however I was wondering if anyone could provide a little more in depth, ie perhaps a photo of how you connected them? This leads to my final question which is whether there is a good place online to buy a few LEDs, a small length of wires, screws and resistors without having to pay about £5 postage for about a £2 order. Thanks for your time and hope this made sense! 
Any further advice on design is also very welcome.
