Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
Prismatic Abstract Geometric Background 2
Source GDJ
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Prismatic Abstract Geometric Background 5 No Black
Source GDJ
Inspired by a drawing in 'Kulturgeschichte', Freidrich Hellwald, 1896.
Source Firkin
From a drawing in 'A Guide to the Guildhall of the City of London', John Baddeley, 1898.
Source Firkin
A bit simplified version. Although it could be edited out to be simpler. Anyway, this time the tiling is converted to a pattern fill -which is using clipping for the tile's edges.
Source Lazur URH
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
A simple circle. That’s all it takes. This one is even transparent, for those who like that.
Source Saqib
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
From a drawing in 'Hundert Jahre in Wort und Bild', S. Stefan, 1899.
Source Firkin
Sharp pixel pattern, just like the good old days.
Source Paridhi
Remixed from a PNG that was uploaded to Pixabay by k_jprather
Source Firkin
Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas