Which modifier for this specific light shape?

Thank you for your detailed replies! seems like optical spot is the way to go. some brands have built in lenses, others require canon lenses to perform (like strobe pro). I am considering built in ones because I am not a canon shooter. Do you think there will be a quality loss?

here is a good experiment.
this looks like the best option, even though it doesn't have the slit Gabo the I need.

 

A legit optical spot has five controls;
1. Aperture, to adjust the size of the projected pattern, more blades means smoother edges.
2. Cookie holder, this plate has slots or clips that allow you to swap out the cookies, which are made of stainless steel with various patterns. Keeping in mind you may be able to adapt other brands of cookies to fit yours. You can make your own out of Cinefoil too.
3. A blade slot to slide in metal blades to cut off the edges. This lets you change a round projected circle into a square, trapezoid or with two blades a slot at any angle you want which is what you are looking for.
4. Focus control allowing you to either blur the projected pattern or make it tack sharp. The better optical quality with reduce chromatic aberrations at the edges of the focus point, slightly defocusing a poorer optic can help if you are not seeking a fine detail in the pattern.
5. Zoom, this lets you adjust the size of the projected pattern with sliding internal optics. It can be useful if you need to place your spot at a particular location and change the size of the pattern.

Some of the above features may or may not be critical to what you require but options you are looking at don’t have the blade slot. You can use flags to give you the slot effect, it just won’t have a sharp transition.

Considering Amazon’s return policy and that price, I’d be tempted to try that one.

 

I would use a pair of cinefoil sheets cloths pinned (c47's) to the side barn doors on a flooded fresnel light. Remember, the closer the edge of the modifier is to the subject/wall, the harder, ie faster shadow edge transition, the edges of the shadows. So I would have it just out of frame.

 

So I ordered the product from amazon. its great. and you can create your diy gobos easily. here are some examples

Imgur
Imgur

 

Could you provide a link to the product you odered?

 

Sure, this is the product. it comes with 6 gobos and 4color gels, its probably not par with higher priced ones, but I got what ı need for a good price!