Remix of 'Buffer stop for piko H0 tracks by alana_chan'.
You will need to remove the crimped fishplate on the rail before fitting. I added a guide tab which slots into the slot between the second and third sleepers and added some blocks either side of the rail for aesthetic reasons. I also added a support block and screw hole at the rear of the buffer stop so it can be screwed onto the layout board.
Just print 'Buffer stop for Hornby 00 tracks.stl' if you just want to make one. I printed at 10% gyroid infil with the model sitting flat on the bed (like how it would sit on the train layout board) with normal Cura support settings (not tree supports).The supports were easy enough to remove with Hemostatic Forceps but needle nosed pliers should work well also.
You can print it on its side if you really fancy it but I would make sure you select the setting Support Placement = Everywhere.
If you want to alter it I have provided the stl's I used in Meshmixer to remove the screw part of the model from the body:
Part - Buffer Stop Body.stl
Part - Screw Tool.stl
... and finally if you want to change the sizes of the blocks or anything else then here is the Fusion 360 archive.