LittleRP Hardware / Software is licensed under the Creative Commons BY-SA 3.0 or greater license:

You are free to:
Share — copy and redistribute the material in any medium or format
Adapt — remix, transform, and build upon the material
for any purpose, even commercially.


Community Forum is a great resource for those looking for guidance with their SLA printer. In addition to general sub forums for everything from hardware to software, there is a sub forum dedicated to the LittleRP. This sub forum will be a primary source for obtaining assistance with any issues or feedback you might have regarding your LittleRP printer.

Our hope is by having a LittleRP forum in an area visited by those knowledgeable in the DIY SLA field that we can grow the community further together.


Downloads / Documentation / Videos

Printer Resources
STL Files – GitHub Link
DXF Files – GitHub Link
LittleRP Part Source List – GitHub Link
Calibration STL Files – GitHub Link

Kickstarter Specific Instructions
1) The lasercut pieces are covered in a protective tape coating (both melamine MDF and acylic pieces) please remove before assembling. If there is any staining on the melamine MDF you can use the white cleaning square with some water or alcohol to remove.

2) A full hood assembly guide is in process, you can tape the acrylic hood together with a few small square of clear tape in the meantime. Do not use normal super glue as it will react with the acrylic, use foam-safe super glue instead. Elevate the hood off of a flat surface before gluing to prevent pooling. The ideal method to glue a hood is to first tack together with blue tape externally, elevate the hood then spot wick in weld-on #3 or #4 acrylic solvent in spots without blue tape. Once tacked in place, remove the blue tape and finish wicking in the acryilc solvent.

3) The build plate will likely need to be roughened for cured resin to adhere, a small piece of sandpaper is included for this purpose.

4) Never disconnect or plug in a motor to the controller board while power is going to the controller. Unplug all USB cables and DC power supplies first. Failure to do this may destroy the stepper driver daughter board.

5) Printed thumbscrews have been replaced with metal ones, these replace the printed part + m4 nut + m4 washer used in the generic assembly guide.

Kickstarter Kit Changes – Imgur Album
Kit Contents – GitHub Link

General Hardware Instructional
Kit Assembly – Imgur Album
Controller Shield Assembly – Imgur Album
Projector Modification – Imgur Album
Projector Mounting – Imgur Album
Leveling the Build Plate – Imgur Photo

Software Instructions
Creation Workshop RC36 – DropBox Link
Software Configuration / Setup – Vimeo Video
Hollowing Models – Vimeo Video
Controller Drivers – FTDI Link

Operating Instructions
Electronic Controller Instructions – Vimeo Video
Basic Projector Setup and Print Process Overview – Vimeo Video

PDMS Mixing / Pouring
- Remove the old PDMS, it should peel off easily after lifting a corner
– Place the petris on a level surface, using a bubble level is recommended
– Mix the 2 pdms parts together very thoroughly, it will become milky with bubbles
– Pour approximately 7g / 10ml into each dish
– Cover the dishes to prevent dust from settling etc
– Wait 24 hours before using

If you want to buy more this is what I recommend: MLSolar Link
(1lb is approximately 450ml / enough for 45 petri dishes)

Supported Projectors
– Acer P1283
– Acer X1240
– Acer P1500
– Acer H6510BD
– ViewSonic PJD7820HD (Same as Acer P1500)
– Hitachi CP-DX250 / CP-DX300 (Same as Acer X1240)

The nice thing about the LittleRP is that it is flexible so if you like you can adapt different models of projectors etc. to it. The main benefit of the models I list as supported is that I have figured out the positioning and mounting in advance for you and verified that they produce enough UV to cure the resin properly. In addition I have verified that the projector can focus close enough and / or provided the hardware needed to modify the projector for closer focus.

It is likely that most bulb based DLP projectors will work with some trial and error. LCD based projectors or DLP projectors with an LED light source will generally not work as they don’t produce or pass through adequate UV levels needed for curing the resin.

If you choose to adapt a model that I haven’t tested the main things you will need to solve are:
– Mercury vapor bulb based DLP for adequate UV output
– How to modify the projector for close focus if needed, you can accomplish this with close-up filters in front of the lense, or by shimming the optics assembly is possible.
– The proper x/y position of the projector in respect to the 90 degree mirror.
– The proper height of the projector in respect to the 90 degree mirror.

With the build plate lowered into position, the goal is to project the projector image through the mirror onto the build plate. Getting the image small enough and centered on the build plate will require some trial and error with projector positioning / height / image focus.

Calibrating Printed Object Sizes
Changing the build size in creation workshop will change the printed dimensions of the part, so there is an initial calibration to get the size precise. The z height of a printed part should always be correct as it is coupled mechanically, but the x/y may be off.

Essentially if the projected image size does not match the x/y build size listed in creation workshop thr printed object will be scretched/shrunk horizontally.
A good way to figure out the proper calibration is to print the calibrationgrid.STL linked above.The distance across the columns (ignore the flanged base) should be 50mm x 30mm. If you measure 49×29 with calipers then you would scale your build size in creation workshop by 49/50 (.98) and 29/30 (.967)  respectively.

Resin Cure Times (Starting Point)


50 Micron Layer / Base

100 Micron Layer / Base

Madesolid Orange Vorex

2000ms / 3750ms

2500ms / 4500ms

MadeSolid Deep Red

1500ms / 4500ms

2000ms / 6000ms

MakerJuice SubSF Deep Red for LittleRP

3500ms / 8000ms

4000ms / 8500ms

GRBL .8a Download

GRBL .8a Values for LittleRP w/o Tilt
$0 = 200.00 (steps/mm x)
$1 = 200.00 (steps/mm y)
$2 = 200.00 (steps/mm z)
$3 = 30 (microseconds step pulse)
$4 = 200.00 (mm/min default feed rate)
$5 = 200.00 (mm/min default seek rate)
$6 = 0.10 (mm/arc segment)
$7 = 255 (step port invert mask. binary = 11111111)
$8 = 25.00 (acceleration in mm/sec^2)
$9 = 0.05 (cornering junction deviation in mm)

Tilt Kit Instructions

GRBL .8a Values for LittleRP with TR8*8 Tilt
$0 = 200.00 (steps/mm x)
$1 = 415.00 (steps/mm y)
$2 = 200.00 (steps/mm z)
$3 = 30 (microseconds step pulse)
$4 = 200.00 (mm/min default feed rate)
$5 = 200.00 (mm/min default seek rate)
$6 = 0.10 (mm/arc segment)
$7 = 128 (step port invert mask. binary = 10000000)
$8 = 25.00 (acceleration in mm/sec^2)
$9 = 0.05 (cornering junction deviation in mm)

Creation Workshop RC54 for Tilt – DropBox Link
ilt Kit Instruction Guide – Imgur Album (in progress)
Controller Shield Assembly (lower portion) – Imgur Album