SMD capacitor looks like this
I did not see "plastic platform" to be sold separately.
But I want such to put under THT capacitor
so that it looks like exactly the way as quarts crystal with the gasket
I just like the way it looks, mechanically holds the the electrolytic capacitor, and separates the cap from the other components.
Does such technique exist for THT electrolytic caps?
I desoldered one of the SMD caps of the required size, and compared the constructions and tried to put THT cap in:
Both models appeared to be covered by the protective material, but up to different point at the bottom - SMD cap is required to be put into the platform/spacer. I also see that it is bad idea to put vias or anything else conductive under the THT cap as it has very small exposed area (however risk of shorting is minimal, just to be sure and have a "good practice").
Putting the THT cap into the SMD cap's spacer has failed: THT is having rubber protruding at the bottom, effectively eliminating bottom of the capacitor seating onto the conductors. However, per datasheet, it is only for some packages:
Smaller sizes are having flat rubber, and must be able to seat into the repsective spacer salvaged from SMD cap.