Noticed on the ender 3 s1 a couple of M3 threaded holes on the front to install a bed handle or other accesories.

So i made this drilling guide to replicate on my ender 3v2 and similar size heating beds. Just have to check the clearance of the heating element tracks. In the pictures the tracks are clearly visible.

I started with a 1/6" drill bit follow by a 3/32" drill bit then a M3x0.5 tap. I messed one of the holes so drilled with a 1/8" drill bit followed by a M4x0.7 tap then clean any burrs left.

Keep it straight and use a tapping guide like the Gridfinity tapping guide by @Zekko.

This could be modified for other bed sizes.

I liked an used this Ender 3 S1 short handle by @Hatebreed26_484118.

BTW, I'm not responsible if you fail to check clearance and drill in to the heating element tracks.