This is a button protorype for MSX computer's keyboard. It doesn't have anything written on it, but a symbol can be put onto the button with a sticker. This particular button is BS (backspace) that will fit the keyboards of Yamaha YIS805, YIS503 or CX5M2 computers. It is also similar to functional keys and special keys used on YIS805's keyboard (STOP, INS, DEL, SELECT, CLS/HOME) With certain scaling it may be used as any other similar button on these keyboards.
UPDATE (April 21, 2019)
I also added the 2-component button's model. The inner part can be printed with a different plastic, for example with PLA - it's less fragile than the one used in the DLP printers. So the outer part of the button can be printed on a DLP and the inner part - on the normal FDM printer. Then the button parts should be joined with some glue.
The outer part of the button should be printed on the DLP printer with the gaps for the letters. Use the bold font so that the gaps are adequately wide to be filled. Then these gaps should be manually filled with the UV-hardened material with a syringe and then hardened under the UV lamp from both sides. I added a picture showing how the button looks like before filling and after filling. There's also the picture of how it looks when completed.
Also I've uploaded the 3-component button where the text and its base can be printed separately on DLP printer using a different color plastic. This component is inserted in the outer part of the button and should match perfectly. The inner part is still good to be printed on the FDM printer. I haven't tried this yet.
A pair of 2-component and 3-component buttons are provided as an example. If someone prints them, please share your experience, thanks.
For the best results the outer part should be printed with DLP printer and the inner part - with the FDM printer. See the description for more info.