Hi Sedona Rocks 
I can best relate from my personal journey's experience thus far and subsequent thoughts upon reflection in hindsight. I use active learning to instill them in memory followed by revision for reinforcement until rote. Other than Guitar Tricks and other online chord resources, purchased training aids were minimal.
The most frequent major, minor and 7th open chord primary voicings are distinctive, and if you think about it even without eliminating the ones seldom used, with only 12 notes in the musical alphabet and 7 in any guitar major scale, 5 in a pentatonic, how many can there be to remember? Once you know those major open chords and other diminutives appear, retention of the latter is boosted by the fact that they are associatively relatable back to a major or minor already ensconced in your subliminal memory. Barres are even easier because the follow easily identifiable patterns all up and down the neck.
For me, when I first learn a new chord, voicing, concept, scale, or song etc, possibly because I don't rush through to the next lesson focussed on chasing max rate of progress, but rather just enjoying myself moving on only once I know that lesson objective competency is achieved and solid, it just sticks.
Active learning paying attention to detail and nuance e.g. the root, the muted strings, how it is best formed, the 'attack' attitudes of my thump, palm and fingers and finessing those -conciously at first, all help it to stick in memory with a degrees of permanence. I reinforce this with revision in the form of chord charts online if necessary, but most importantly, lots & lots of playing in songs which is the relatable practical application which coincidentally places the focus on the assimilation process being fun. This just cements them it in mind and muscle memory without it being a conscious dry slog. In the week or so after initial learning something new, I will use chord and scale charts if necessary for cross referencing in my active revision every day, but the need is usually minimal. Mostly reinforcement through active application in playing indelibly imprints them for me.
Conjunctive to active learning through play, the key to building and retaining that foundation in my experience, is don't try to learn everything at once. i.e. Every chord or permutation thereof. Make up or print off your own charts of only 4~8 new chords at any time, or each of the permutations of a scale one at a time, and learn them as iterated in my preceding paragraphs. Only then move on to the next new material challenge. Before long your growing chord 'alphabet' will seem as familiar and easily recited from memory as the 26 letters of the English alphabet do to you now.
All that said, a comprehensive chord chart or poster on the wall or tablet etc is a useful training aid as long as you use it actively focussing on the 'don't try to learn/remember them all at once' paradigm. Ulitimately, recall needs to be from conscious memory which with sufficient repetition will transition to subliminal, not any chart. The latter is just like training wheels on a bicycle, best discarded ASAP rather than relied upon beyond the minimum necessary.
Cheers 😎
