Is the cedar one of the native usa cedars, Western Red, or aromatic cedar. I am buillding a bench out of the native aromatic red cedar, locally called eastern red cedar. Legs and bench top are width of tree diameter, around 18 inches and 3 1/2 inches thick. It is from a old dead tree. Cut wood with chainsaw sawmill, and smoothed with had plane then scraper blade then sandpaper.
Using linseed oil many coats, then a liquid wax that contains bees wax and other waxes. Having trouble sealing the end grane where it does not want to keep soaking it in. but looks great. Do not know how it will look after months or years.
+--- Sanding Sealer on the end grain...
But it sounds like your application is different than the OP. Since other people are jumping in here asking other questions, maybe more detail is needed(?)
Species of cedar are found around the world. Spanish Cedar, Iranian Cedar, Chilean Cedar, Japanese Cedar, Lebanon Cedar, etc. Not just in North America. Cedar is commonly soft and has oils inside it that make it desirable for exterior, or to line closets and chests. I like the way it looks for paneling and trim. It gives a Northwest feel to things. Cypress and Juniper are related somehow and also get lumped in as being called Cedar in some locals.
It is somewhat challenging if you want to stain or finish it by hand for interior work-- if you start using it for furniture and move away from it's traditional natural look and feel. It does do spray-on well, but because of it's qualities that make it a good exterior wood, those same qualities make it a challenge for what you consider using interior finishes. It is a wood that for interior trim or paneling, we usually just wipe it with a light oil, or with no finish and let it gray with age. Since is is soft, it is easy to work with...
Next is that the oils that give it good weathering and insect resistance outside, play heck with interior stains and finishes. Without care and good prep, it will turn out splotchy trying to use interior stains on it. Usually you do a natural look to it.
It is a soft wood, so things you do to try to toughen the grain would help. Those same things help it take interior stains more evenly.
Next challenge after that is that if you are using it for a dining table, then you start wondering if things are food safe. Tung oil and Linseed oil... There are lots out there that are not pure
and are mixed with other things to use as driers, that the things mixed in are not food safe. Those types that are marked as food safe are still toxic until after those driers
dry and the oils cure. Some brands take 7 days. Most take about 30 days. But the note of doing that with cedar, is that the wood has to be warmed up enough and kept that warm for that finish to work with that wood. (about 75*F)
As Charles mentioned-- Epoxy or glass would be ideal for what you are trying to do with that.
That is assuming that that is a soft species of cedar. Cypress is harder, but has even more oils to it.