I made one by, you bet, removing the fan from one that had it (as part of an electronics swap) 😀
Result wasn't bad according to my finger vs the heatsinks (unplug first!!!), certainly better than the AMD 286@12 at which the only (system) fan was loosely aimed by the designer, though this was a "modern", integrated graphics and I/O 286 system...
A few months ago I found some parts in the garage and assembled an ATX P2 Celeron 433 system, also fanless because when we replaced the fuse back in 2007 or something (yes it ran then-fully-updated XP) we forgot to reconnect the huge and relatively quiet fan inside, it held at least 20 minutes but then it started smelling of hot dust like most TVs, so I had to stick a fan outside it until the next day (after spending the night unplugged) to reconnect the internal one 😜