When it is warm outside the main concern with resin printing is ventilation. During winter we have to make sure the resin stays at an adequate temperature as well (usually 20-25°C for budget resin and 25°C+ for engineering resin).

One balanced option is to have the printer in a garage while not venting till after printing has finished; this keeps fumes outside the residence and provides the opportunity for efficient heating. A printer in the residence can be heated, but heating the air that is instantly vented is not efficient.

Adding a small heating pad is a safe and cheap method to raise the temperature of the resin during printing. Raising the temperature in a warmer environment can still be useful for engineering resins and reducing the exposure time on budget resin.

When temperatures begin to drop, even the 6.5 W heating pad will be able to adequately support budget resin.

The small heating pad becomes insufficient near-freezing temperatures. For a cold garage, an enclosure and a higher wattage heat source will be needed.

A grow tent enclosure provides only a minimal increase in the resin temperature during the warmer times of the year. However, it will aid in proper ventilation.

When temperatures begin to drop, the added insulation of the enclosure becomes apparent. There is a ≈1°C increase in the resin.

At freezing temperatures, the enclosure will bump the resin temperature up by ≈2°C, but the ≈17°C resin is still below the recommended levels. The resin can print at this temperature but the exposure times and risk of failure will be higher.

Swapping the small 6.5 W heat pad for a larger 18 W variant will raise budget resin into its recommended range.

This heating pad can be attached to the interior or exterior of the acrylic cover, with the former being more efficient. You can use various attachment methods such as kapton tape, nylon string, or zip ties so long as the pad is not punctured. 

Adding more wattage will heat up the enclosure and resin faster but you have to be careful. Here you can see where a 250 W ceramic heater pointed at the printer will heat the resin towards 60°C. Beyond ruining the resin, this can damage electronics, warp plastic components, waste electricity, and start a fire.

An efficient manner in which to manage the 250 W heat source is by using an inline controller or by purchasing a specialized unit.

You will be able to place the controller within the enclosure and set your desired temperature. In this example, the heater outlet is parallel to the printer and the controller is on the far side behind the printer. Placing the controller's sensor probe too close to the heater's outlet will result in a lower resin temperature and placing it far away will heat the resin above your set temperature.

The lower winter temperatures will lower the variance in the resin temperature. In this and the prior example, the target for the controller was 30°C. The prior example allowed the resin to rise ≈5°C above while this one is ≈1°C above.

The temperature-controlled heater will provide the best results to keep the resin at your desired target, but this method is more expensive to employ and uses more energy than the heating pads. Make sure that the controller you choose is rated for the power draw of the heater.

This particular setup utilizes an open-air ventilation setup in a separate and sealed indoor room. The grow tent keeps the heat in and allows printing without the printer covers. A wide grow tent, such as the one pictured, has plenty of room for multiple printers or a wash and cure machine.

The heat source is one of the small Lasko heaters with an Inkbird controller - you can see the sensor probe dangling from the top of the tent. For this setup, the controller is set to kick on when the temperature drops below 28°C. It will then run until it surpasses 32°C, where it will turn off and wait until it drops again. This keeps the entire grow tent near 30°C while reducing the wear on the controller.

This is the internal temperature of the grow tent setup above with an ambient temperature of ≈4°C. This test was conducted without the additional heat output of a resin printer and with minimal to moderate convection (drafts) on the outside of the grow tent.

This test demonstrates that a 200 W heater will max out at ≈26°C under ≈4°C ambient. However, it reaches 20°C+ within 10 minutes of starting up.
We will be conducting additional tests in the near future.