Universal cap with handle

### Purpose
This is a _universal_ cap for any kind of circular opening which you would like to close with a cap. The cap is held in position through gravity only, so it is only for openings which point upwards to the sky.

You can and should**(!)** primarily customize the **inner diameter** of the thing you want a cap for because this is the critical thing here. Default (and depicted in photo) size is **20.7 cm** inner diameter. It is unlikely that your needed cap will have the same default diameter. I added **0.2 cm** to the diameter to make the cap fit a 20.5 diameter, but I guess **adding 0.1 cm** would have been sufficient.

### Customizing
Then you can customize everything to your needs. Following properties are adjustable.

* cap_diameter_inner (in cm) — _ABSOLUTELY NECESSARY TO BE ADJUSTED!_
* cap_height (in cm)
* cap_wall_size (in cm)
* hole_diameter (in cm)
* hole_screw_head_length (in cm)
* hole_screw_head_diameter (in cm)
* hole_hexa_radius (in cm)
* hole_hexa_depth (in cm)