v_kyr

See also About layers!
 

Well things might do change over time, who knows the market will show. - BTW, in the past all better graphics hardware platforms were Unix based expensive workstation ones (Silicon Graphics, Apollo, Sun, HP etc.) and most capable graphical software (also bloody expensive) was therefor only available on/for those platforms. Later as plain cheaper consumer hardware got more and more powerful, things did changed over time here and a bunch of former times only for Unix available commercial graphical software was migrated over to PC systems. Ironically nowadays were Unix (aka Linux derivatives, FreeBSD etc.) itself got's cheap most commercial graphical or other specialized software isn't any longer available for Unix based systems (beside maybe OSX).
 

There are so many things wrong with your understanding of all this.
1) When you put a pixel layer on top of another pixel layer (and assuming that the Blend Mode is "normal" - the default value) then the top pixel layer will completely obscure the bottom layer. Anything you do to the bottom layer will NOT be visible, because the top layer is obscuring it.
2) When you put an Adjustment Layer on top of a layer, or on top of a stack of layers, it applies itself to whatever is visible from below. If you have a pixel layer with a mask, and another pixel layer beneath it, an Adjustment Layer at the top of the stack will apply itself to whatever portions of the 2 layers are visible.
3) If you want to limit an Adjustment Layer to just 1 layer, you have to drag it "into" that layer, so that it becomes a Child of the layer. This limits its effect to that layer, and ignores the other layers.
So...
When you duplicate the picture and apply a mask to the top layer, you have revealed the duplicate below. In other words, the net total is still the original picture.
If you put a Layers adjustment on top of all that, you are applying the Layers adjustment to whatever trickles up to meet it - in this case, you are applying the Levels Adjustment to the equivalent of the original image.
To do what you are trying to do, duplicate the original photo, add a Levels adjustment, and then drag that Levels adjustment over the top layer so that it becomes a child of that layer. Then, any changes will only be seen on the layer which "contains" the adjustment.
If you add a mask to the layer with the adjustment, you can hide part of that layer to reveal the UN-adjusted layer underneath. (see my screenshot)

Some layer usages can also be influenced (how to be added for certain operations/tasks) via Assistant Manager settings.

If added a tutorial on my YouTube channel which demonstrates how to draw the dodecahedron with polygon shapes with five sides.

Here is a template for an A4 sized prism desk 2019 calendar created in AD. The calendar dates used in this template do stem from Mensch Mesch. - The ready glued together calendar looks like the following ...

... the A4 Affinity Designer template looks like this ...


... and here is the corresponding AD template file ...
prism_A4_calendar_2019.afdesign Have fun!

No chance actually.

A bunch of services do offer ready to reuse PDF templates, just one example for Avery templates here:
Avery Templates

Here is a template for an A4 sized prism desk 2019 calendar created in AD. The calendar dates used in this template do stem from Mensch Mesch. - The ready glued together calendar looks like the following ...

... the A4 Affinity Designer template looks like this ...


... and here is the corresponding AD template file ...
prism_A4_calendar_2019.afdesign Have fun!

Here is a template for an A4 sized prism desk 2019 calendar created in AD. The calendar dates used in this template do stem from Mensch Mesch. - The ready glued together calendar looks like the following ...

... the A4 Affinity Designer template looks like this ...


... and here is the corresponding AD template file ...
prism_A4_calendar_2019.afdesign Have fun!

Click on the Popup list which shows the "Layout" options in your screenshot, there a bunch of others in the shown list, between these are "Scaling and ArtBoards" which allows to setup different scaling options. Also there on the list the "Paper handling" choice has an option for adapting to the used paper format etc.

With this Affinity Designer template you can create your own Dodecahedron 2019 Calendar.

If you want to plot just the Dodecahedron you can export the plot data as a SVG-File only. (I use this template on a Brother ScanNCut Plotter thats the reason why I choose 96dpi as resolution.)

If you want to use my calendar template you can print only the print data, which you will find in the layers Druckdaten and Plotmarken. (I use the plot marks to justify my plotter)

You can download the template here: Affinity Designer – Dodecahedron Calendar 2019
Keep on drawin'
Norbert
 

However ...

How did you previewed the exports, with which tools on what OS? - Under OSX for example the Apple Preview app opens exported EPS files as PDF with a white background. A tool like GraphicsConverter instead shows the same correct as an EPS file with transparent background.
So it might depend on the tools used to preview the exports and how these handle this.

AFAIK no, there is no such feature.

Well my suggestion would be to not use those bitmaps at all in a vector tool like AD, things will look much better when you use kitchen tool vectors here for creating a kitchen tool border.

Here are some vectors you can reuse instead (copy/paste them into a new document and arrange, size, rotate etc. them to your likes) ...
Kitchen tools vector illustration set.afdesign  
BTW, the net is full of such vectors sets (free and commercial) just do a search and make sure they are reusable vectors instead of bitmap drawings.
 

See also here Kitchen Utensil Silhouette ideas etc. - However when you download such vector sets from the net make sure they are in some by AD supported import format (SVG, EPS without embbed Ai, PDF). If you type into the Google search "vector kitchen tool border" or "vector kitchen tool frame" you will get hundreds of example links to inspect. - Good luck!

Well my suggestion would be to not use those bitmaps at all in a vector tool like AD, things will look much better when you use kitchen tool vectors here for creating a kitchen tool border.

Here are some vectors you can reuse instead (copy/paste them into a new document and arrange, size, rotate etc. them to your likes) ...
Kitchen tools vector illustration set.afdesign  
BTW, the net is full of such vectors sets (free and commercial) just do a search and make sure they are reusable vectors instead of bitmap drawings.
 

v_kyr -
"... looking at them made me now just having cravings for such fancy chocolates"
My daughter just started a business making these chocolates. If you happen to live near Port Townsend, WA in the United States she'll be happy to whip up a dozen or so for you.
I get to help her by sharing my three lifelong passions: photography (semi-pro hobby), product marketing and promotion (profession), and eating (joy!).
 

This (cross-platform development and following OS related UI standards) is one of the keypoints and the overall difficulty for development here.  GUI excessive software which initially has been designed and been implemented just for one major OS, is always hard to port over to another different OS. There are a bunch of possible pitfalls you have to deal with here, since every OS has it's own style guides and frameworks. Even basic programming language (C/C++ etc.) compiler associated based libraries (their functions/routines) can behave OS related different here, or there is no real 1:1 äquivalent available for some lower level functions etc. Not to talk for GUI related framework differences between the OS'es here you ideally have to adapt to and fight with.
And even if you planned from ground up to be cross-platform compatibel with your software, by using things like Qt etc. to overcome some of the UI problems that might arise, the devil is in the detail here.

Yes it's not pretty and looks always bad to the eyes, even without the scaling issues. The above shown Illustrator settings seem to offer alternate settings for corner handling ...

... so boxes look symmetrical. Also they seem to scale up/down correctly from what I can see above.

Well the overall problem for implementing this (1 + 2) is to have a clever and foolproof transfer/change/update mechanism, which isn't that easy to handle from a programmatic viewpoint here for single objects. Since sharing and editing single objects with keeping their whole attributes (vectors, pixel, position, size, colors, filters, masks ... etc.) would probably need to be handled on a sort of referenced/shared object layer base here as a common denominator between the apps. Meaning an "Edit with" here would have to transfer the corresponding objects layer between the apps in some locked/released and changed/update way.

Had a doodle on this...
Some serious blur and transparency effects going on here 

@v_kyr I am glad that my "Pressed & Embossed" styles I converted from the asf file are useful to you
I used exactly the same styles to make an example picture

Not necessarily, but a 3D render software offers of course much more options and possibilities here. - You can also tweak simpler things (shapes) with a 3D effect in Designer, as @souacz said above. To do so you would make for your button example a rounded rect shape and apply some metal style to that, then apply a FX 3D effect and some embossed text or signs etc.