What you need

1/2 inch conduit pipes 4x10ft

All sizes are for 350mm 8mm rods which will give you a bed size of 250x250mm.

To use different rods add/subtract length difference of rods from horizontal pipe sizes.

Cut pipe sizes:

Pipe locationPipe size for 350mm guiding rodsQuantity
All frame pipes along X except back bottom pipe508mm3
Frame back bottom pipe514mm1
Frame bottom along Y511mm2
Frame top along Y389mm2
Bed support505mm2
Z rails475mm4
Frame Z support back485mm2
Fame Z support front470mm2
Gantry for motor mounts413mm1
Gantry for idlers3811
Gantry along Y448mm4
Part DescriptionNumber of partsPart Example
8mm linear motion rods4
linear motion bushings (bearings) for 8mm rods8Example
608 ball bearings20
Nema 17 motors6Nemas example
Lead screw couplers4Example
8mm Lead Screw 450mm+4Example with nuts
Lead screw nuts4
GT2 6mm Belt5 metersBelt Example
GT2 idlers 3mm bore toothless2Example
GT2 idlers 3mm bore with teeth 20 teeth6Example
GT2 Motor pulleys 20 teeth2Example
Zip ties8+
For Extruder E3D V6 J-Head1 or 2 depending if you want single or dual extruderExample of hot end
12V/24V 40mm fan1Fan example
3D printer control board1Board I am using
Or newer 32 bit board1SKR 1.3
DRV8825 stepper drivers4 or 5 depending if you making single or dual extruder versionStepper drivers
12V 30A or 24V 15A PSU112V PSU
To be continued ….
FastenerQuantityPart example
5/16 1 inch or 25mm M8 bolts16
5/16 1.5 inch or 40mm M8 bolts4
5/16 or M8 nuts20
M3 10mm screws for Nema 17 motors24
M4 10mm screws for PSU mount4
#6 3/4 (or M4 20mm) screws and nuts112
#6 1 1/2 (M4 38mm) screws and nuts12
#6 1'' (M4 25mm) screws and nuts16
#6 1'' (M4 25mm) flathead screws and nuts4
#6 1 1/4 (M4 32mm) screws and nuts11
For Idlers 3mm bore #4 1-1 1/2 (M3 25-38mm)8

For new 500mm+ upgrade of Piper 2:

For 350mm rods, bed size is 23mm smaller on Y and 13mm smaller on X due to larger carriages. So 350mm rods will produce bed size  237x227mm. If you want bed size of 500x500mm you will need rods at least 350+(500-237)=613mm on X and 350+(500-227)=623mm on Y. Then to calculate the required pipes add delta 613-350=263mm  to all pipes along X and add 623-350=273mm to all pipes along Y.

Pipe Sizes are the same based on 350mm length of rods with exception of:

Pipe locationPipe size for 350mm guiding rodsQuantity
All frame pipes along X except back bottom pipe514mm3
Frame back bottom pipe along X520mm1
Gantry for motor mounts419mm1
Gantry for idlers419mm1
Bed support511mm2

There is also small 2mm difference for UK version for frame pipes along Y axis which may be ignored (frame pipes for 500mm+ version along Y axis are 2mm longer for UK version)

Other parts:

Part DescriptionNumber of partsPart Example
12mm linear motion rods4Example
linear motion bushings (bearings) for 12mm rods8Example
GT2 10mm Belt5 metersBelt Example
GT2 10mm idlers 5mm bore toothless2Example
GT2 10mm idlers 5mm bore with teeth 20 teeth6Example
GT2 10mm Motor pulleys 20 teeth2Example