required tools: turning lathe, 3(2) cutting chisels, drills
tips:
.do NOT make this part longer than 14,6 mm, otherwise you will not be able to fit it in the steering tube
.the 15 degree angle of the three bevels is given by using a cutting chisel with 30 degree ( Spitzmeißel)
.it might be useful to round the edge of the bevel which is nearest to the tube (nearest cutting chisel in the drawing)
…austrian homemade…
bigger+bonus here:
s769.photobucket.com/albums/xx33 … ria/hbrb2/
Best regards
Improved 2012 version, made of aluminium Ø 12 mm Torradur AlCu4PbMgMn,
black anodized by Ing. Alfred Prägler Vienna
How to make this buttons:
lathe front face, using middle/high spindle speed
set length scale to zero
set length to about 17 mm
lathe diameter (high depth of cut can be used)…
…to about 10 mm
measure, set diameter scale to zero
lathe to diameter 8,0 mm
last cut at low depth of cut…
…and slow feed motion to achieve fine surface
lathe diameter 6,5 mm, length 13,4 mm
lathe diameter 5,5 mm, length about 3 mm
change chisel position to achieve 15° cones/bevels,
set both scales to zero while touching the front edge, lathe the first bevel to 4,0 mm diameter
lathe the second bevel to 4,0 mm diameter, length 1,8 mm
lathe the third bevel to 4,0 mm diameter, length 5,8 mm
cut out rest material…
…between length 1,8 und 5,8 mm carefully…
…to diameter 4,0 mm
exchange chisel, set spindle speed to low/middle, finish the front face
round the edge of the third bevel carefully using a smooth file
some polishing at high spindle speed
slow spindle speed cut off, length 14,7 mm plus chisel broadness
change chisel, finish back face of 8,0 mm collar at high spindle speed
break the edge, using sand paper
pre-drill the 2.0 mm spring hole with centering drill
drill 2,0 mm hole to 6,5 mm depth
Finished button pair…
…and machine, EMCO compact 5.
Last but not least the titanium version, made in Germany by request…
…and the weights.
thanks for the idea, i copied it (sorry, without your permission) and it’s very good, the folding / unfolding is become much easier than before.
Many thanks for the feedback, I’m indeed happy that you enjoy the buttons! 
You need not to be sorry, if I would want to be asked for permission or something like that,
I would not have published the drawing. 
Btw, if somebody is not able to create such buttons by himself - pm me.
I use a normal alumunium rod (found somewhere scattering in workshop), it is little bit soft so dent is unavoidable, next time I will make from harder material, like stainless steel or bronze to make it better.
And the 30 degree angle is crucial, i didn’t use that, so the button must pressed exactly from center, if not, it will stuck inside.
Naturally, due to the (relatively soft) aluminium will these buttons wear out sooner or later.
But I think it’s better the buttons wear out than the holes in the steering tube.
That might happen if you use harder material.
I mean more important than the 15° angle is to round the third edge of the buttons, a lightly bevel could also be made by using the file.