
I love Solemn Simulacrum's design. It's a colorless way to ramp, though it isn't the most efficient way to do so. It draws you a card, though you need to get it into combat or sacrifice it somehow, so it isn't the most efficient there either. A 2/2 for 4 that doesn't otherwise impact the board directly may not be the best use of your mana. But mana and cards are the two basic resources in Magic, and this does a little bit of both.
Is Solemn Simulacrum the best card in modern Magic? No. I have cut it from a lot of Commander decks. It needs a better reason to stay in deck lists. Maybe you have synergies with artifacts; maybe you have sacrifice or reanimation effects; maybe you are simply building a lower-power deck.
While pondering Solemn Simulacrum's strengths and weaknesses, I had the idea to create custom versions for each color. I wanted to explore ways to make a Simulacrum that still did its basic ramp-and-draw thing, but in a color-specific way. So I did!
What is Solemn Simulacrum? What about it is most notable?
There are many ways to define this, but I chose to anchor to these characteristics:
I used MTG.Design* to create the mockups below. This is the best site I've found for creating custom cards in a web browser. It has some ability to manipulate art as well as save cards that you've made, but I didn't mess around with those features for this small batch of cards.
* Future editor's note: Card Conjurer is the superior custom card creator these days, in my opinion.
Solemn Simulacrum would already work fine as a white card. In fact, it half-exists already: Kor Cartographer is a 2/2 for 3W that gets any Plains card onto the battlefield. But we can do better than a common originally printed in 2009.
White does sometimes ramp with treasures and/or as a punishment for your opponents (think Smothering Tithe and Monologue Tax), but I couldn't think of a way to make this a meaningful enters-the-battlefield effect, and for the sake of variety I wanted to include land-based ramp in a color that had it available.
White can also ramp by returning cards from the graveyard. Sun Titan is a classic example, but more recent cards like Sevinne's Reclamation and Restoration of Eiganjo do so as well. This was very intriguing to me—I love Eiganjo's design—but it wanted the abilities to be backwards, i.e. draw on enter, ramp on death.
In the end, I settled on something closer to Stoic Farmer, itself an upgraded form of Kor Cartographer in most ways. My design also plays into the catch-up mechanic present on a variety of white cards like Knight of the White Orchid and beyond.
Drawing additional cards is more common in white than it used to be, but in general, each white card may draw you one additional card unconditionally, or one per turn under certain conditions. Again, Solemn Simulacrum already works as a white card; see Outlaw Medic for a recently-printed example of that.
To differentiate my design, I looked to another mechanic: blink and flicker effects. Casting Cloudshift on Sleek Simulacrum draws you a card in addition to its Plains-searching effects. This is treading new mechanical ground, but I don't think it's likely to break anything. As a bonus, an opponent exiling your Sleek Simulacrum will always give you a card back.

Blue doesn't do land-based ramp much. A few blue cards make your lands produce more mana, like High Tide or the recently-reprinted Reset, but it's just not a focus of modern design. Blue does have some cost reduction effects, usually for instants and sorceries (like Baral or Mocking Sprite), but this is difficult to represent as an enters-the-battlefield effect.
Instead, I turned to mana dorks for this design. Blue isn't as thick with mana dorks as green is, and it has restrictions on the things it can use the mana for, but they are perfectly acceptable modern abilities. A common restriction is to require you to spend the mana on artifacts (like Soldevi Machinist and Oaken Siren)* or abilities (Omen Hawker and James, Wandering Dad). In the end, I went for a combination of both: Sonic Simulacrum copies directly from Renowned Weaponsmith.
In order to make the mana dork ability relevant, I looked for alternative ways for blue to draw cards. My first thought was to create Clues directly. Clue tokens are pretty blue, and pretty common in modern Magic. I decided that it would be annoying to try to get Sonic Simulacrum killed with its own mana available in order to use it on the Clue tokens, and drawing a single card felt too weak, so I put a Clue-like ability on the creature itself. It's now in line with cards like Witching Well and Sarcomite Myr.
Sonic Simulacrum invites comparisons to other famously flexible blue cards like Mulldrifter. An evoked Mulldrifter is fair but strong, and the ability to add on a 2/2 flying creature is great. Sonic Simulacrum can draw 2 cards for 6 mana this turn, or 2 cards next turn for 4 mana, or act as a mana dork for artifacts. With vigilance, it can attack and still do all of those things.
* Soldevi Machinist was way ahead of its time. Its only printing was in Ice Age in 1995. One additional blue-dork-with-restrictions was printed in Darksteel (2004), but it took until Khans block in 2015 for these kinds of designs to see frequent print.

Black's ability to ramp is somewhat limited. Yes, Dark Ritual was printed in Magic's original set, but this kind of effect is now mostly in red. Yes, a small number of cards get more mana from Swamps specifically, like Cabal Coffers and Crypt Ghast, but these are rare and are closer to static abilities than one-time effects.
Where else can we look for ramp in black? Treasures are present in every color, but are far more common in black and red. Skullport Merchant is a recent example of a simple Treasure generator in black. Additionally, a major part of black's color identity is "power at a price", which frequently manifests as "sacrifice a permanent to get a benefit". Various cards like Pitiless Plunderer generate Treasures when a creature dies.
Can we combine those two things to create a ramp ability that feels very black? Certainly. Ruthless Technomancer already does so. In fact, this ability was so interesting that I lifted it entirely, with two small changes: Sinful Simulacrum can sacrifice itself; and it creates tapped Treasure tokens to prevent things from getting out of hand.
Black can draw cards just fine, though to reinforce its "power at a price" theme, it often loses life at the same time. Scrapwork Rager, a 4-mana 2/2 that draws a card at the cost of 1 life, is a great comparison for our new design.
Like blue's Sonic Simulacrum above, Sinful Simulacrum has decent flexibility. If you play it on an empty board, it's a deathtouch blocker or two Treasures and a card, similar to designs like Big Score. With additional creatures lying around, you have even more options.

Red ramp usually comes in two forms: Treasure tokens and ritual spells like Seething Song. Some permanents do add red mana directly, like Brazen Collector or many Chandra planeswalkers, but I found it difficult to create a simple effect for this, so I settled for Treasure generation.
I looked at Treasure-making abilities on existing red creatures to find a clear and fair effect. Each card has its own design and its own way of generating Treasures, but they can be categorized into three main groups:
An enter-the-battlefield effect would have fit fine for this design, but I opted to grant a Treasure on attack, making the haste keyword more important. And hey, now you can generate more Treasures on future turns if your Swift Simulacrum survives, though you have to weigh that against using it as a blocker.
The design of draw effects in red is pretty clear: you need to discard a card first, like Tormenting Voice; or you need to play your newly drawn cards quickly, like Act on Impulse. To ensure you always have opportunity to use the drawn cards, I opted for the "impulse draw" option, and used the most permissive version of the effect to give you at least one turn to play them.

You might think that a green Simulacrum would be easy to design. Green already ramps via lands, just like the original Solemn, and already draws cards for (mostly) creature-related reasons, including death (Silverback Shaman for example).
That's nice and all, but I wanted to differentiate this design from both Solemn and white's Sleek Simulacrum, which are already similar. Green doesn't just do land ramp, it also has access to mana dorks, and these usually don't come with restrictions like their blue counterparts. However, most mana dorks come in under 4 mana, and for good reason: you're intended to use cheap creatures to cast your bigger spells. If you already have 4 mana available, you probably want to cast bigger spells, not more ramp.
Yes, there are counterexamples. Some 3-mana elves tap for GG, like Fyndhorn Elder. Some 4-mana creatures in this vein exist, like Undermountain Adventurer (GG + the initiative) and Canopy Tactician (GGG + stat boost). I couldn't find a spot that I liked for any variation on these effects, though. Tapping for two mana felt too weak; tapping for three mana felt too high compared to the other Simulacrum designs.
So, I went with a classic land ramp spell. I used the Nature's Lore template, which can fetch any Forest card and does not put it into play tapped. There are some recent examples of green cards like Sowing Mycospawn that can fetch any land at all, not just Forests or basics, but I think this Forest-focused effect feels more green.
The draw effect is identical to Growth Spiral, a blue-green card, but other mono-green cards like Explore and the new Insidious Fungus have similar templates, so I think it's a perfectly acceptable usage here.

It's easy to get lost in the sauce of design. This was a well-defined problem—five cards, similar effects—and it still took me a lot of time to research and execute. Scryfall, as always, makes the process easy for everyone.*
Sometimes old cards still hit a great balance of fun and interesting. Sometimes new updates to old cards clarify Magic's intentions for each color's strengths and weaknesses. I certainly tried to do so myself.
I tried to keep each card at a medium power level and relatively balanced with each other. I know they're not perfect, and some are more reliable and flexible than others, but hopefully they are close enough to compare. I will happily accept comments on templating, power level, or other ideas for these effects that I may have missed.
* I encourage donating to Scryfall if you can. This is not something I say lightly. Scryfall is incredibly well-designed, does not display ads except for numeric card prices, and is the backbone of my entire Magic hobby.