Resin 3D Printing

We charge £5 for the Resin Printing Induction, and 20 pence per gram for printing. This allows us to build up a war chest of funds for inevitable part replacement in the future.

The process for getting the Resin Printer induction:

  • Become a member of So Make It.
  • Request the Resin Printer Induction on Slack in the #3d-pug channel
  • Wait for contact from a volunteer Resin Printer Superuser who will arrange to carry out the induction.

Resin Printing Induction


So Make It has an Elegoo Mars 2P MSLA Resin Printer and an Elegoo Mercury Plus wash and cure station.  This printer is able to print in significantly finer detail than the Lulzbot FDM printers but have a much smaller print area and are more expensive to run.  The printer uses UV light to cure each layer of UV resin.  Each layer is displayed on an LCD screen in the base which screens out some of the UV so only the intended area cures.  Each layer separates from an FEP layer at the bottom of the resin bath and gradually builds up the object upside-down.

The Wash & Cure Station will both wash the part to remove excess resin after the initial print process, and further cure the print with a stronger UV light source.


The slicing software is CHITUBOX 1.9.4, which is installed on the space PC near the Vinyl cutter.  To slice, launch CHITUBOX and either drag in or open an STL file.  Unlike with FDM printing, the smallest amount of surface area should be exposed to the bed – otherwise it might not separate properly from the FEP sheet.  Flat surfaces should be oriented at about 30-40°, particularly the first few layers.  Support material is then used to support the part – you can view the supports using the print orientation and supports tabs.

Supports can be automatically generated as light / medium / heavy. The heavier the support the thicker they are, and the less of them there are. Heavier supports are also embedded/attached to the print better. Supports can also be selected as ‘all’ which puts them between the build platform and the part – and between aspects of the part itself, or ‘platform only’ which puts them between the build platform and the part only.

The print can also be made hollow, and internal supports added. However hole(s) facing the build platform should be made using the ‘dig hole’ function. This lets out resin that would otherwise be trapped, and also prevents ‘suction’ that will pull the print off the build platform.

With resin printing, both the colour and formulation of the resin matter for slicing.  We have a grey profile for the grey resin we have been provided, if using another resin you may need to create and modify a profile to get one that works.  You may also need to modify the profile as the weather changes as the resin will behave differently in the cold.  Most of the settings currently are a good default.

Exposure time of the gray resin is set to 3 seconds per layer, and ~30 seconds for the initial layer. This should be good for the colder environment during winter, we may be able to reduce these in summer. Other resins will vary. 

Click on ‘Slice’ – this process is quick, but the ‘Save’ takes longer. Always save locally first and then copy to the SD card so that the Slicer has a quick enough device to write to. A USB key with a rubber cover has been provided which is mostly to stop resin running down the front of the printer and getting into the USB socket.

If you are finding that prints are failing for no apparent reason, then re-orient the print on the slicer.


Resin should be poured into the resin container located on the base of the printer. Do not fill past the ‘max’ line – ideally can fill it much less than that which will prevent the resin going all into the ball joint mount of the build platform. More resin can be added while the print is in progress if needed.

We can leave resin in the printer if we wish, stir it a bit before printing if resin is already present. Shake the bottles before adding any more – bubbles will rise to the top of the resin pool (the print is created at the bottom next to the FEP sheet).

The build platform should be cleaned with the supplied scraper. It is important that there is no cured resin on the build platform because it will damage the FEP sheet at the bottom of the resin pool. If the FEP sheet is damaged then resin can leak into the rest of the machine which is a disaster.

If the space is especially cold (below about 5-6°C) you should not print.  If it is warmer than that, but still cold, it is a very good idea to warm the resin bottle by submerging it in warm water for 10-15 minutes before adding it to the printer.

The build platform of the printer can be leveled if need be, although we should aim to leave it in place.  If required, the platform is mounted on a ball-joint which can be loosened. Drive the platform down to the bottom to level it and tighten the screws again.

To print, take the USB stick with the file on it and put it in the front of the machine.  Press “Print” and choose the file you sliced earlier.  Then tap the “play” triangle. The print will start – the printer will beep a bit, and the first few layers will take much longer due to the extended cure times.  As the print progresses it should be possible to hear a ‘cracking’ sound as each of the layers separate from the FEP sheet (but remains stuck to the build platform).  If any cured resin gets stuck on the FEP membrane at the bottom of the resin pool then it should be ‘popped off’ by flexing the membrane from the bottom. Do not use tools to remove it as the FEP membrane is fragile.


Once the print is complete, it is not fully cured. This enables removal from the build plate and supports to be removed. Wear gloves for this process, masks are recommended.  Do not get resin on your clothes – short sleeves are probably wise, as it is easier to wash uncured resin off skin.

Wash the part in the ‘dirty wash’ container. This contains ‘ResinAway’. Remove the turntable plate from the Wash and Cure station if present.  Place the print in the ‘chip frier’ cage.  Place the ‘clean wash’ container with the mixer in the bottom on the wash station and slot the chip frier into the holder above that.  Set the wash and cure station to ‘wash’ (press “mode” until the symbol on the screen is two drops with arrows between them) and ensure the lid is on.  Set the time to 2-3 minutes and press start.

There is also a bracket for lowering the build platform into the wash station. However this should only be used for cleaning the build platform when it really needs it so we don’t contaminate the build plate with ResinAway.

ResinAway is reused (see Maintenance) so don’t throw it away.


Next the part can be finally cured. Place the wash/cure station into cure (image of a light bulb) mode and put the turntable back in place. Put the print on the turntable and put the yellow plastic over on the machine. Cure the part for 2-3 mins.

Clean up

Ensure that any resin spills are cured with the UV torch, removed, and thrown away.  Use the plastic scraper to remove any residual resin from the build plate.  Turn everything off and replace both lids.  If you don’t think the printer is going to be used for 4-5 days and there’s more than a minimal amount of resin left, then pour it out (via a funnel and filter) back into the bottle.


The ResinAway tubs only need cleaning if they start to fail to clean the prints properly.  When that happens they should be exposed to UV (with the torch, cure station, or by sitting it outside for a long while) and then filtered through a coffee filter (use the specifically marked jug).  After this has been done a few times, move the “clean wash” ResinAway to the Dirty Wash ResinAway and dispose of (resin removed) the Dirty Wash.  It would be good idea to drain the basin and check the state of the FEP sheet when doing this.

If you have a print that fails or the resin has been in the print tray for a while, then filter it and return it to the original bottle.