Pulse jet engine overview
There is a "pulse jet" as a method of obtaining jet propulsion. This principle has been introduced in many experiments in which a hole was made in the lid of an "empty can (bottle)". This principle is called the "Kadenacy effect".
The "pulse jet engine" was devised as an engine that constantly generates thrust by utilizing this principle. Although it was developed as a flying bomb at the end of World War II, it is now mainly used for radio-controlled engines due to its low thrust and intermittent operating noise. In addition to aircraft applications, it is used in water heaters, hot air fans, and hot water boilers by taking advantage of its simple mechanism.
Structurally, there are two types, "Valve (check valve)" and "Valveless".
Both types require a fire (ignition system) and combustion air supply in addition to fuel to start. After starting, they will operate on their own, so these will not be used.
It seems that "gasoline" is often used as the fuel for "with a valve (check valve)" and "propane" is used for "without a valve".
Since the structure is simple, many people make their own, and many manufacturing drawings and manufacturing methods for that purpose can be found on the Internet.
● "Valve" pulse jet engine
This is a form of "front intake" and "rear exhaust" for the purpose of jet propulsion.
The "check valve" discharges the combustion expansion gas only to the rear and also serves to pass the intake air when the pressure is reduced after the discharge.
Check valves have "Petal valve", "Reed valve", and various other structures.
"Petal" are often used for small models.
The Venturi effect is used for "gasoline vaporization" and is placed in front of the "check valve".
An example of a "Petal" pulse jet engine is shown in CHAPTER Ⅰ, "PJE-01".
This is about the same size as the model engine that is actually sold.
An example of a "Reed valve" is shown in CHAPTER Ⅱ, "PJE-02".
● "Valveless" pulse jet engine
It has a very simple structure composed of pipes of different sizes and lengths.
In many cases, only the "fuel supply line" is connected, and "Open flame" and "Compressed air" are directly supplied to the inside of the engine for starting.
An example of a "Valveless" pulse jet engine is shown in CHAPTER Ⅲ, "PJE-03".
This is about a quarter scale model of what is available on the internet.

CHAPTER Ⅰ "Petal valve" pulse jet engine (PJE-01) model

CHAPTER Ⅱ "Reed valve" (PJE-02) model

CHAPTER Ⅲ "Valveless" pulse jet engine (PJE-03) model (1/4 scale)

B. Assembly Manual (PDF format, total 13 pages)
The detail assembly manual including "Parts-List", "After printing treatment" and "Assembly procedure" are prepared based on "Standard Skill (Filing, Drilling, Tapping and painting)".

C. Purchase Parts Information;
　- Screws
M1.4, M2, M6 , Tap required
Quantity and length can be adjusted by your experience.

D. STL file
　　Total STL files are 14+3+10=27 items including the stand and tools.
　　“ws” of last 2 digits of file name means “With Support” special designed.

E. Total Net Print Time: Approx. 23+3+15=41 HR
　- (Estimated as case of PLA, 0.4mm Nozzle, 0.2mm Layer Height, 40% infill and No raft and support)
　　Note: When at actual print, each parameter may be adjusted by your experience.

F. Printing settings
　　Raft, Support, Layer Height, Infill: Depending on your experience.
　　My models were printed by "idbox" using with 0.4 nozzle, 1.75 PLA.

I do hope your success!!