npm i -g @angular-devkit/schematics-cli

schematics schematic --name exemplo

schematics blank --name meuSchematic

{
  "$schema": "../node_modules/@angular-devkit/schematics/collection-schema.json",
  "schematics": {
    "meu-schematic": {
      "description": "Exemplo de um Schematic",
      "factory": "./meu-schematic/index#meuSchematic",
      "schema": "./meu-schematic/parametros.json"
    }
  }
}

{
  "$schema": "http://json-schema.org/schema",
  "id": "MeuSchematic",
  "title": "Parâmetros do Schematic",
  "type": "object",
  "description": "Exemplo Schematic",
  "properties": {
    "nome": {
      "type": "string",
      "description": "Nome do serviço",
      "$default": {
        "$source": "argv",
        "index": 0
      },
      "x-prompt": "Qual é o nome do serviço que você quer criar?"
    }
  },
  "required": ["nome"]
}

import { strings } from '@angular-devkit/core';
import { apply, mergeWith, Rule} from '@angular-devkit/schematics';
import { SchematicContext, template, Tree, url } from '@angular-devkit/schematics';

import { Parametros } from './parametros.d';

export function meuSchematic(_options: Parametros): Rule {
  return (tree: Tree, _context: SchematicContext) => {
    const sourceTemplates = url('./files');

    const sourceParametrizedTemplates = apply(sourceTemplates, [
      template({
        ..._options,
        ...strings
      })
    ]);

    return mergeWith(sourceParametrizedTemplates)(tree, _context);
  };
}

import { HttpClient } from '@angular/common/http';
import { Injectable } from '@angular/core';

const API_URL = '/api/<%= dasherize(nome) %>';

@Injectable({providedIn: 'root'})
export class <%= classify(nome) %>CrudResourceService{

    constructor(private httpClient: HttpClient){}

    findAll():Observable<any>[]{
        return this.httpClient.get<any>(API_URL);
    }
}

npm run build
schematics .:meu-schematic  --debug=false