In a perfect world, everyone would use a well-calibrated lab oven capable of reaching temperatures up to 350C. However, a variety of equipment can be used for 3D printing purposes, even as simple as a 55C filament drier.

In this space, “ovens” are usually pressed into service to dry filament (typically 55-80C) and anneal semicrystalline plastics (typically 120-180C). More advanced filaments may require temperatures even beyond these two.

Just because a piece of equipment has a temperature gauge does not mean that the chamber within that equipment is perfectly evenly heated to that temperature, nor does it mean that the temperature of the filament/plastic/parts within that chamber will be evenly heated up to and not beyond that temperature.

Oven temperature gauges may indicate the temperature of the air entering the chamber, may be roughly estimating the temperature in the chamber, or may be hiding significant hysteresis (continual temperature overshoot/undershoot). Further consideration must be made for “hot-spots” within any oven - rarely does an oven heat evenly internally, especially after placing (large) objects inside. Finally, special attention must be paid to infrared heating of components exposed to heating elements, which can cause the objects to heat far beyond the temperature of the air in the oven.

Off-the-shelf, purpose-built filament dryers are generally only really useful for low-temperature materials (PLA, TPU, etc.). There are a few exceptions, such as Sunlu's E2 dryer, but most are effectively overpriced food dehydrators. Many of these options don't fully reach their advertised maximum temperatures and/or don't have sufficient airflow internally to be effectively remove moisture from the filament. They can be a decent solution for storage while printing, but are not recommended for actual drying. Annealing is not an option with these dryers.

An increasingly popular option for filament drying and annealing is an air fryer. Some popular models include the Ninja AF101 and Gourmia GAF716. These provide a compelling balance of affordability and maximum temperature. Since they are forced convection ovens, airflow is also quite good as well. The main drawbacks of a stock air fryer are usually the preprogrammed “cooking” profiles having short maximum durations with no option for full manual control. The hysteresis of several common models can be found on RTings.

While using your standard kitchen oven for drying and/or annealing may seem logical and convenient at first glance, the downsides end up outweighing the convenience heavily. Most kitchen ovens are prone to having large temperature swings (sometimes +/-20C or more), as well as significant temperature inaccuracy. Another concern with using a kitchen oven is contamination. Since polymers release various VOCs (volatile organic compounds) and particles when heated, it's generally not a good idea to mix that with food.

Lab ovens are the best off-the-shelf oven option for drying and annealing. They are known primarily for high temperature precision and stability. A relatively affordable option for a convection lab oven would be this one from Amazon. Out of the box, temperatures can be held within +/-1C and is additionally well insulated. This oven is capable of up to 300C and will run for as long as the user needs at any temperature. If choosing a lab oven, cheaper ones (such as the one linked above) lack ramping/soaking programming. Instead, the user manually controls the heat-up and cooldown rates.

The accuracy, stability, and precision of any “oven”, especially basic air fryers or toaster ovens can easily be improved by utilizing a PID heater controller in place of (or alongside) the original electronics. This will allow for more precise temperatures, smaller temperature swings, and also unlocks the ability to program specific heat-up and cooldown curves over time.

!!WARNING!! Modifying an oven will almost certainly lead to working with (wiring controlling) mains voltage (like many hotbeds). If you are not comfortable with mains voltage, and/or unable to learn to be comfortable working with mains voltage, DO NOT choose this option. MAINS VOLTAGE CAN AND DOES KILL PEOPLE!

When replacing the stock control unit in an oven with an aftermarket PID controller, there are two main paths to consider.

Utilizing a Raspberry Pi (or similar SBC), Kalico/Klipper can be used as control software for an oven. The chamber temperature is essentially controlled in the same manner as a standard bed heater in a 3D printer and can be programmed in various patterns and profiles.

For a less DIY solution, there are a number of off-the-shelf PID controllers on the market that can be used on their own to add ramp/soak functionality to various oven types. Some popular options are the DIN 1/16 form-factor Auber Instruments SYL-2353P and DIN 1/4 form-factor Novus N3000. Inkbird sells a complete kit with the controller, SSR, thermistor, and heatsink all in one here (though this does not support programmable ramps)

Many other projects have been created for this purpose such as PIDKiln, the Controleo3 convection oven kit, and this project on Hackaday.io.