A quart of screen paint on amazon can cost about half the amount as an actual projector screen.
Use a projector on tan concrete wall.
Once you buy all the materials it should cost less than 50 for the paints needed.
This is a permanent solution as it will involve painting the wall so i only suggest you do so if you are happy to proceed on this basis.
Using the wall first will give you an idea of how big of a screen to get.
But there is another option available which is to use an outdoor wall.
The best solution for using a projector on a wall is to paint the wall with a projector screen paint.
Using an outdoor wall as a projector screen.
The tan wall will make the image look warm so just use a cooler white balance.
The projectors can be of great help when working on uneven surfaces.
Some use them for only a certain complicated section of their painting while others make the whole mural using them.
The issue with this type of paint is that it s not cheap.
In conjunction with photo editing software they help you map out plan and design according to the difference in elevations bumps and gaps in the wall.
It is not 100 necessary but it allows the wall to reflect the light more efficiently.
I have a 92 pj screen that has 2 slideable brackets at either end that can hold 4 screws in each bracket but the screws can not be any thicker than 6mm or the wont go through the holes i think the whole screen weighs about 13kg.
Start at 6500k and go up until the colors look decent.