V3.0 Update:
Modified the rollcage to be a bit more solid and have less openings. Means a little more weight but also means less annoying support material.

V2.1 Update:
Added screw holes throughout the chassis for mounting various armour upgrades.
Also replaced the stand with a better version that should prevent the bot sliding off.

V2 Update:
Found an issue with Rollcage. He had a knack for getting stuck on his back, in the vertical position.
To fix Rollcage, this version has a tapered rear end now to help stop him getting stuck.
I also added some screw holes in the rear of the chassis for mounting some armour. I used some 1mm Lexan sheet, cut to size with some tin snips.

This is my 3D printed design of a bot used in our 150 gram Antweight combat league. I've named him Rollcage.
Rollcage is about as simple as you can get for an antweight bot. He is a standard wedge/pusher bot and is perfect for anyone looking to get into some robot fighting. We will be using the Rollcage design to make a few spares for newcomers to try out and fight with.

This bot leaves a little for you to customize as far as the internal components go but please use this list of components that I used as a guide to get you started:

• 2x 50:1 microgear motors. http://botbitz.com.au/index.php?route=product/product&path=64&product_id=55
• 2x Pololu 42x19mm wheels. https://www.robotgear.com.au/Product.aspx/Details/300-Pololu-Wheel-42-x-19-mm-pair-with-rubber-tread-tire
• 2x brushed ESC's. http://www.ebay.com.au/itm/131645159656?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
• RC trigger style 2 channel transmitter and receiver. I am using a Flysky FS-GT3C in the below video but this Hobbyking transmitter is cheaper and will work just as well. https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=72930
• 260mAh battery (this higher capacity is only used so it can go several matches without a charge and Rollcage had plenty of weight to spare). http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=37342
• V-Tail Mixer. https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=46730
• Power on LED (optional because ESC and receiver lights are visible).
• Power on switch (robot fighting requirement).

Assembly:

• Print the chassis and two of the offset microgear motor mounts. Add supports in the chassis and motor mounts as required.
• Carefully break away the support material.
• Give the parts some acetone vapor treatment (optional).
• Wire up the motors to the ESC and connect their supply to the battery connector and power switch.
• Add a power on LED if you want. (With an open top, the lights from the ESC's and reliever provide more than enough power on indication).
• Carefully put in the motors and ESC's inside the chassis. Secure the motors with the motor mount clamps. Use a couple small self tapping screws to hold it down. I used spare screws that came with a couple standard size servos.
• Connect the receiver and mixer to the ESC and insert into chassis.
• Hold everything down with some hot glue if required. I found that everything sat pretty snug inside and no glue was necessary.
• Connect the battery and insert into chassis.
• Attach the wheels and you're done!

Here's a build video of Rollcage:
https://youtu.be/YQmMvlJW1rw