Front Flipper Robot. This is a 150g combat robot. Very simple build that doesn't require many extra tools.

I'm attaching the .STEP file as well for those who want to edit and modify. This is designed to fight nondestructive robots. Flippers, hammers, wedges, etc. You will need to modify a bit for full combat and 0.5mm titanium wedges for example.

Assembly tricks:

I use a paper clip to attach the flipper to the servo arm and cut off the excess after its bent.
However tapping the servo arm to accept an M2 bolt is ideal.

The lego hub has tolerances to printed easily on my printer and be a snug fit, but attaching a tighter tolerance version incase you need it.

I use #3 for the top brace and wedges

BOM:

Hardware:
3qty M3x12 (https://amzn.to/3cb8L3Z)
1qty M2 x12 (https://amzn.to/2V8CfZ7)
Small Zip Ties (https://amzn.to/2UQZYy8)
Paper Clip
HotGlue/Superglue
3-24 Plastite Screws (https://amzn.to/2AInL9z)
Wheels: Lego 24x14 Tire (https://amzn.to/2yLfDUd)

Tools:
M2 Tap (https://amzn.to/2RhQ4TY)

Electronics:

Flipper Servo: KST DS315MG or KST DS215MG
(https://alofthobbies.com/kst-ds315mg-servo-48kg-666-oz-in-07sec-high-voltage.html)

You can use other servos like the Corona DS929HV for a cheaper alternative. However, you will need to play with the linkages to get full travel as they often come with a shorter servo arm.

Drive Motors: N20 Micro Gearmotor 30:1 or 1000rpm (https://amzn.to/2JsTwpA)

ESC: Endbots DESC
https://www.endbots.com/collections/products/products/endbots-desc?variant=5580585992221

RX: Your choice the Endbots DESC comes with a Spektrum receiver built in.

TX: Your choice. I use a Spektrum DX6 (https://amzn.to/2qk8RQA)

Battery: Nano-tech 300mah 2S Lipo Pack (https://hobbyking.com/en_us/turnigy-nano-tech-300mah-2s-45-90c-lipo-pack.html)

You can buy these wheels to save weight if needed. Although the lego wheels work great and are much cheaper

SC-2110p ProComp (http://www.132slotcar.us/store/product_info.php?products_id=4523)