These are skids are an accessory for Gyrobot's quad frame the Spyda 500. http://www.thingiverse.com/thing:160607 I have designed version 2! http://www.thingiverse.com/thing:897644 I was hoping the Crossfire quadcopter skids would fit, but the holes and angles are in the wrong position. These are are made for the Crossfire version of the Spyda 500 frame plates because that is the version I have. Feel free to remix into your own version.Your printer bed must be very close to 200mmx250mm. You will use the whole bed and you will need to print the bottom skids on the diagonal. Mount them to the frame by using a bolt 7mm longer than what you are currently using in the motor arm. The skid arms may need a little filing to fit into the bottom skids. The short end of the skid goes to the front and the long end to the back. This places the midpoint of the skid at the midpoint of the motors. You can glue them if you like. In PLA you can try printing the arms with 2 shells and 50% fill and the skids 35-50% fill. These files should print with no support on a well tuned printer, but it can help on the tip of the bottom skids.