The way construction works is by giving various doll and equip classes resource thresholds, within these thresholds, anything can drop.

Equipment#

So all-150 can yield any part, while anything with ammo ≥151 will exclude golden crit scopes. If you want, you can fiddle around with it and click together what you need.

However, given its empirical 5* drop rate of ~10%, 150 / 150 / 150 / 150 really should be your default go-to recipe for general purpose construction unless you really need something specific at the exclusion of anything else.

T-Dolls#

T-Doll recipes are a tad more complex. Thresholds can be either per resource, or as sum of all resources:

 Again, there's an interactive calculator to click together targeted recipes.

Regular construction is straight forward: For non-HG rolls, use the minimum recipe, and if its resources are below or at 920, add enough resources of any kind to get over the threshold to exclude HGs. Similar, for HGs, sticks to the minimum recipe.

Heavy construction comes with a few caveats: While it doesn't drop 2* dolls, you must spend cores on it, and ten times as many resources as on regular construction. Drop rate, however, only seems to be about two to three times as high for 5* dolls. There isn't really much use for it outside of rolling for shotguns.

Official Recipes#

Speaking of drop rates being shit, due to excessive salt coming from the player base, Mica has released officially recommended recipes:

They seem to be working rather well, from all we can tell so far, but you're free to use voodoo regardless.

Voodoo#

GFDB scrapes the ingame "last constructed" recipes and builds a database that records how well they work. If you want to craft a specific thing and believe in the powers of voodoo, refer to it… just keep in mind that even the best recipes tend to have a success rate of under 5% for specific 5* targets. And also keep in mind that 5% success rate is not the same as "I'll get one after 20 attempts".

Uncensor#

For various reasons (mostly dumb legal stuff), MICA decided to hide the full uncensored artwork behind a construction recipe as switch. To see the unnecessarily slutty original artwork, start a construction using 522/320/404/137 as recipe, then quit the game and restart it. It'll then download the additional artwork and you can see 9A-91's panties in their full glory. You pervert.